Limbo's Inhabitants

There are two primary races dwelling on Limbo, the slaadi and the githzerai. The slaadi have apparently been here forever. The githzerai adopted the plane as their own at some time in the distant past, so long ago that they are effectively natives. Primes have some knowledge of these two races, but they make the mistake of thinking them the only dwellers in Limbo. What they don't realize is that Linbo is surprisingly well populated by the sorts of beings they're used to thinking of as their neighbors: humans, elves, dwarves, halflings, gnomes, and such, as well as orcs, goblins, trolls, and their ilk. Limbo is as well populated, in fact, as any of the Outer Planes, inculding the Outlands. It's just that the nature of the environment tends to make the inhabitants a bit more insular than elsewhere. 'Course, a cutter traveling through Limbo is also fairly likely to encounter a Chaosman or two. They come here in droves to let the spirit of randomness soak into them.

The Powers

Besides those powers who make their home on this plane because its chaotic nature matches their own, Limbo also hosts a number of powers with highly elemental spheres of ability. Apparently, they choose Limbo rather than an Inner Plane as their home because Limbo isn't so single-minded in it's elemental nature. Powers who have chosen Limbo as their home plane include Agni, Vayu, and Indra of the Indian pantheon, Shina-Tsu-Hiko and Susanoo of Japan, Fenmarel Mestarine of the Seldarine, and Tempus of the Forgotten realms pantheon. Rumors persist of slaadi deities named Ssendam and Ygrol, but the slaadi have devoured all investigators.

The Proxies

The powers of Limbo don't seem to care too much what happens outside their specific realms. On the rare occasions that they feel the need to send a proxy, one's chosen at random from among the power's petitioners.

The Petitioners

Various legends repeated among the Clueless claim that spirits that end up in Limbo are just swept up into the background chaos. Sometimes, those legends say, a bunch of that spiritual energy collects together and gives rise to a chaos elemental. Chaos elementals are supposedly these vaguely humanoid lumps sprouting all sorts of tentacles, horns, trunks, hooves, claws and whatnot.
Sure they are. As usual, the Clueless have taken a smidgin of truth and fabricated so much of a story around it that the final product bears no resemblance to the original.
In the case of Limbo's petitioners, the reality is far stranger than the fiction. Each petitioner on Limbo is an individual being, with its own personality, and usually its own distinctive features. The problem is that those features can be extremely difficult for a normal person to pick out. As a matter of fact, normal people often have difficulty even recognizing that a petitioner is present. That's because Limbo's petitioners are as chaotic as they come (not surprisingly). They don't have any one particular natural form: rather, they're each a living: thinking, clump of primal chaos matter. But whereas chaos matter often remains in an indetermined state, Limbo's petitioners are always manifesting themselves as something specific - a pillar of flame, a misty whirl of air, a dashing wave of water, a column of rock, or some mix of these things. They just don't remain in any one form for long. In fact, they cange forms unconciously, as fast as their moods change. And their moods change mercurially.
Sometimes a petitioner can be persuaded to helk a body who's in trouble. They have a real fascination with stories, especially those with lots of action, and they're willing to pay for a good one by providing some service to the teller. Or, if a basher can convince a petitioner that there's a really good story to be learned in the adventure he's currently involved in, a petitioner may come along just to watch it unfold. If the basher's lucky, the petitioner might even chip in with a helping hand on occasion, just to coax the story along. But don't count on it. the real trouble to all this "story for a service" practice is that Limbo's petitioners are so frivolous they're likely to get distracted by something else without a moment's notice and forget about the deal they've made. A basher has to be very careful to hold their attention if he want's them to hang around. It can be as frustrating as trying to herd chickens.
Now, about thos tentacled and horned beasties - well, they exist but ain't petitioners. they're chaos beasts, and a berk'd be a complete leatherhead to think she could fight one of them!

The Slaadi

Other have written about the skin color of the various slaadi, their combat abilities and the like. And they've mentioned the slaadi's strict hierarchical society, in whihc the strongest rule those weaker with a cruelty that is all the more terrible for its casualness and lack of passion. But slaadi society and psychology certainly bear more discussion.
For most humans, it may be easiest to compare the slaadi to barbarian nomads. The creatures have loayaltey to nothing but their own kind, and have respect for no other culture. They seem to view all other creatures as beasts to be used as the slaadi see fit. Slaadi cannot be reasoned with, or bargained with: they cannot be bought off with tribute nor appealed for mercy. Like the Fated, they consider themselves to own whatever they can take. In part, this is because of their physiscal relationship with the plane of Limbo. The slaadi are all innate anarchs. They are perfectly at home in the raw chaos of Limbo's primal matter. But while all of them can breathe and move in that chaos, virtually none of them can sustain it in stable form without concentrating. On the other hand, they don't really need much for survival, basically just food - in their case, meat. And they're such great hunbters and fighters that they can catch whatever food they need among Limbo's native animals.
This has led the slaadi to develop as creatures that have no real need for possessions and that respect only individual strength. Some souls have characterized them as basically giant, carnivorous frogs that just happen to be able to talk - and that description is fairly apt. But the slaadi fight for two reasons. The first is for food: the second is to prove who's the toughest. The creatures are so wrapped up in this reverence of individual strength that it leads to some odd behavior on their part - at least as far as most humans would judge.
First, the slaadi see nothing wrong in stronger member of their race forcing a weaker member to do its bidding. Weaker slaadi would never think of banding together to overthrow a bully, the way that humans do. Instead, the yconsider the stronger slaadi's right to bully them.
Second, while slaadi typically run together in groups while hunting or raiding, they never actually cooperate in their combat. If four slaadi were facing one human warrior, for instance, they would take turns fighting that soul. Only if the first slaadi were defeated would the next begin to fight, and so on. (Usually, though not always, the weakest of the slaadi is the first to fight, allowing the stronger ones to stand back and judge the opponent's mettle.) On the one hand, this means that one good fighter could conceivably hold off an entire hord of slaadi. Eventually, of course, the slaadi would come to revere that fighter's powress and treat the cutter as their better (though they're likely to then go and get an even tougher slaadi to come try the cutter's mettle). On the other hand, it means that the slaadi don't even flee from weaker creatures, even if outnumbered. Even as they're being cut down, they continue to expect that their strength will win out in the end.
The lesson is, a basher who's expecting to be running into slaadi should either be certain that he's the toughest thing on two feet (or four hooves, for bariaur), or bring along lots and lots of friends.

The Githzerai

The githzerai aren't really native to Limbo, but they've been on the plane for so long that they've become just about the next best thing to it. Originally, their ancestors were humans ensalved by the evil illithid race. But at a point in the far distant past, they were lead to freedom by a great female warrior named Gith. But upon gaining that freedom, the people immediately became divided. According to legend, a man named Zerthimon stepped forward to accuse Gith of being unfit to rule the newly freed slaves. Gith, zerthimon said, was evil and would lead the people to ruin. A great battle was fought between the two factions, in which Zerthimon was killed. But his followers fled to Limbo, where they became the githzerai. The rest of the people became known as the githyanki, and took up residence on the Astral Plane. The two groups have hated each other ferociously ever since.
Because of their history as an oppressed race, and a splinter group of it at that, the githzerai are a suspicious, insular people. Unlike the githyanki, they aren't evil. but they are certainly not at all friendly to outsiders. They burn with the fires of fanatical faith in their rightness, personified in their apparently immortal leader - the self-styled god-king or Great Githzerai, Zaerith Menyar-Ag-Gith - and acted out in frequent raids upon the githyanki. To the githzerai, these raids are viewed as a matter of survival. They believe that if they don't keep the githyanki perpetually off balance, that evil race will put in motion a plan to obliterate the githzerai completely.
Not surprisingly, then, the githzerai have little interest in other things. According to their views, they have no timne or energy to devote to friendships outside their race. This means that cutters who visit a githzerai city feel always on the outside of things, and continually scrutinized as a possible agent for the hated githyanki. That isn't to say that foreigners are completely unwelcome in githzerai settlements: the cities value trade, and can't afford to risk sending their own citizens to conduct it outside of Limbo. But each githyanki city has a portion of its area devoted to foreigners: the rest is completely off limits to all non-githzerai, unless they are escorted by a githzerai, and that doesn't happen very often. Bashers who want to circumvent this rule should keep in mind that, as a race, the githzerai are exceedingly intelligent and hard to fool, and that they have no compunctions against killing offenders.
As intense as the githzerai are, some souls find it difficult to understand them as chaotic neutral in alignment. But the githzerai people are so focused on their survival that they simply have no interest in debating larger matters of good and evil. And while they are fiercly loyal to their race and ultimate leader, it is the loyalty of individuals, not the compliance of slaves. The githzerai always carry with them the memory of their origins, and they despise the thought of slavish obedience to an overlord. "Better the heartfelt devotion of a free soul than the gruding obedience of a slave" is a commonly repeated githzerai saying.

The Xaositects

Limbo serves as the primary plane of influence for the Xaositect faction. they're thick here. A cutter can't swing a dead cat on Limbo without hitting one of the Chaosmen. But they don't really do anything on the plane - they don't maintain a citadel, don't get much involved in local politics, don't seem to work toward any particular end. Apparently, they just come here to revel in the eternal newness of chaos.

Other Encounters

Over the ages, lots and lot of humanoid beings have found their way to Limbo. Many of them stayed there: some even survived. As they learned to come to terms with the chaotic environment, and to fight off periodic attacks by the ferocious slaadi, they began to establish strongholds and settlements on the plane.
In some cases, these settlements began with a fairly cosmopolitan nature, as members of widely differing races encountered one another in the primal soup and banded together for mutual defense, against the slaadi in particular. There are, in fact, cities in Limbo that count among their citizens orcs as well as elves, goblins as well as dwarves, besides humans and halflings, for example. In such cases, the alliances that keep the city functioning are uneasy at best, their only real unifying factor being the fear of slaadi hordes. When slaadi raids are few and far between, the citizens often begin warring among themselves. 'Course, not all these cities are so schizophrenically mixed. There are examples of elven/human cities, elven/halfling ones, human/dwarf towns, and so on, going about their business in relative peace and tranquility - barring slaadi raids.
In other cases, settlements began as a single extended family, then grew from there into a full-sized town. These communities tend to be very clannish in nature, with a strong distrust or even hatred of all outsiders. (This is especially true of purely orc or goblin strongholds, of course.) In some cases, settlements such as these have been isolated from the rest of the universe for so long that they believe themselves to be the only intelligent beings in existence (not that that's a very intelligent attitude to take). In their view of things, the primal soup of chaos is the only stable spot in existence. Often, they are ruled by a quasi-religious order of anarchs who seek to keep the rest of the population in ignorance concerning the ways in which intelligences can shape that chaos to their own will. It can be quite a shock for such people when a stranger suddenly tumbles into town and starts blabbering about a whole universe full of other intelligent creatures.
It's worth noting that not all of these settlements have anarchs to maintain them. In some places, all that keeps the terrain stable is the fact that someone is always assigned to concentrate upon doing so. That is, there are special shifts of guardians assigned to just sit for a few hours at a time and maintain the terrain. If they were to stop, the town would just dissolve right away right from under them and all their neighbors. It's not a terribly secure way to live, but for locals it's better than drowning in the soup.
The upshot to all this is that in Limbo a cutter can encounter just about any sort of settlement imaginable, and then some. this one of the things that makes the plane a fascinating, though often deadly, place to explore.

Animals

Animals on Limbo fall into two general categories: those native and those transplanted. Native animals are those able to survive in the primal soup and they include such things as: The fearsome chaos beast

The shelled krackadoon (no image; The shelled Krackadoon is a limbo-dwelling mollusk that feeds on stray chaos emitions. Their shells look like solid chaos, filled with spirals, loops, jagged edges and fractal nonsense.)
The webwinged maugway (no image; The cheerful Maugway is a creature made of transparant sails, which it uses to steer similarly to (but better than) a winged krackadoon. Maugway have froglike bodies with eyes on stalks, and no limbs. Natural anarchs, they tend to live in stable bubble-areas filled with gases of seemingly random type. Maugway are terrified of bright light, gibbering and laughing.)
The horned Zhisto (no image; The Zhisto is an animal that seems to be all horns: antlers, rhino horns, giant ram horns, bull and gazelle horns, unicorn horns and more all arranged in fantastic winding shapes that curve around each other in mazelike patterns. Zhistos drift randomly through the plane of ultimate chaos, feeding on much of whatever the soup happens to be at the time. It is, however, very fond of the vegetation in anarch-shaped lands and is quite a pest there. It chews things with hornlike teeth in the center of its horny body, which means it can usually only get at long branches, tall grains, and grasses.)
Such creatures swim and crawl their way all across the place, infesting soup and stable terrain alike.
Travelers in Limbo notice however, if they're alert, that some of the examples of prime-plane-type terrain they come across have prime-type animal life, and some other examples of it don't. If they're really sharp, they'll realize, without being told, that the animals always exist in inhabitated terrain, and never in the free floating, spontaneous bits. There's a simple reason for this. Limbo's primal matter can spontaneously manifest rock, dirt, streams, coulds, and even plants, but it doesn't do animals. An diwth the exception of those beings with a passive chaos-shaping score of 29 or above, no one on Limbo is capable of willing animals into existence. however, most regions that are maintained by anarchs have been seeded with animals carefully gathered from off the plane. 'Course, if these regions were ver allowed to decay back into Limbo, the animals would perish.
Because animals have been deliberately brought to the plane to seed these inhabitated areas, the dwellers there are very careful in how they are handled. Rulers of these areas punish poaching with a ferocity to make the worst prime world sovereigns seem like nannies and wetnurses.