make more posts, I'm not 100% on this but when I signed up there were 3 avatars so I didn't bother with one, now I have the choice of 68. I guess it would be like that so newbies wouldn't take up heaps of space in there profile, make one post and then never post again. I notice that there is an option thats says, selecting this will delete your custom avatar, so I assume that in 30000 more posts I might be able to get my Cujo pic up there. :questionm
This is a very early implementation of something I plan to expand upon later. As Cujo stated, we have quite a large number of avatars but in order to use them you'll have to make more posts. I think it's a bit silly, so instead of having it as it is currently, I'll make all the current avatars available to everyone regardless of their posts and add borders on preexisting avatars to give them a kind of special status for visitors with more posts to their account.