I have a set of themed Monkey avatars. I was thinking a monkey holding a brush for designer. for coders maybe holding a cog etc and a range of monkey themed avatars expressing different emotions. Because they are all consistent in theme they could be placed in their own catergory.
Here's a preview of some (below)
These are monkeys holding a paintbrush only, though, I could easily alter them with other icons. Being .png and transparent they would look flawless with no redundant background on all of your styles here. They are 80x80 pixels so they are following the dimension rules allowed here both in size and in kb.
As for pre-defined avatars, you have 5 or so catergorys of predefined avatars already. Anyway, I think they would work well here with some design alterations which I would be willing to undertake.