[quote=Primal Conundrum]I'm toying with the idea of just saying "No furries or creatures parodied in the Twilight novels"
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This is what I would recommend. Animal races are usually very derivative and predictable. You take the stereotypes connected with the animal and just project them into a culture. Cat folk are lithe and graceful, ratfolk are greedy and sneaky, and waspfolk are assholes. Vampires and werewolves, on the other hand, are simply overdone and it is wasteful to drag them into a boundless game when you can't throw a stone without hitting a vamp/wolf rp. It's like when a redneck goes to an authentic Italian restaurant and then orders hamburger and fries. Quite rageworthy. 

One thing you could do is provide more base information about the world and its themes. How does magic work, what is the general technological level, what is the cosmology like (are there gods, spirits, otherworlds or whatever). If you provide this skeleton you might get more coherent ideas from people. Like if I say magic is all animistic (relies in some way on spirits), technology is early Renaissance, and the cosmology is dualistic with a material and spirit plane, then from that you still have infinite options but the things people come up with will seem to be part of the same world.