Alternative races are very enjoyable to build.
My own 'setting' (read: Stuff I want to make into a setting eventually) includes:
Humans: In various roles, from kingdom-dwellers to jungle-dwellers.
Ulari: Tall human-looking beings with a few serpentine features (mostly superficial). They tend to take on the roles of diplomats, rulers, and leaders, or, when they fail to find affluence, skilled weavers and artisians, due to their high dexterity. They have a screwy gender ratio (1 female for every 4.5 males) that keeps them working in unison for survival, leading to a odd variety of reproduction-based societies, from queendoms with chosen, elected, or victory-based mating rights, to male harems, to females being used as captive breeding stock, with their use being sold to the highest bidders for vast sums. Their charm-resistance-numbing venom gives them a sinister edge, no matter how good of beings they are, and their weakness to cold gives them amusing tendancies to cuddle with warm or hairy people or animals.
Burunjhu: Smallish race (just barely small enough to be 'small',) with feathers for hair (including body hair, which is the same on males and females), Romanesque noses (beaked-looking), and clawed fingers and toes. They're horribly clever, but have an innate irritability and sense of personal emptiness that makes them horrible leaders and diplomats, and weak performers and spontanious spellcasters. While they're agile, their clawed fingers mean they're no better than a human at manipulating objects. They mostly exist in nomadic clans, something like gypsies, sans that they sell ideas and information instead of charms and fortunes. They're like cranky, roaming intellectuals.
Chitinoids (Naming in progress): Bearing two sets of eyes, one for Darkvision, one for Low-Light and normal vision, as well as a carapace-style body that affords a tiny natural armor boost. I'm still working on some details, but they're a very nature-oriented species that tends to use animals to a great extent, but can't consume meat. I may make them the first species to discover the idea of harvesting milk. More urban ones tend to work in stables and zoos, keeping the animals happy.
Mistlings: A naturally shapeshifting species that are, basically, protist people (as such, they lack any of the resistances one gains by being a more magical shape-shifter, as it's tied to their actual physical substance). Their most common forms are grayish, conical lumps with a single large, black, disk-shaped eye. They usually just bask in marshes and such and conversing. With some time and effort, however, they can change in to a variety of forms (though with largely the same stats), allowing them to roam around as quadrapeds (usually when they want to carry a lot of weight) or bipeds of various shapes, but their normal size. Though they can look like spongey gray humans, they usually prefer a mouthless newt-like humanoid shape. I'm thinking of giving them some sort of healing or disease-curing ability requiring some self-sacrifice ("Here, eat my hand, and you'll most likely survive that illness.")
Sizeshifters: (Naming in progress) Small-sized fae beings that can shift in to medium-sized forms when they need strength more than dexterity. As they have long, (hairless) donkey-like ears, they have great hearing. They're pretty much tree-hugging hippies, but much more pastoral than elves. Almost like lazy forest hobbits.