Ok, it was for me a little joy to create a few new avatars, you might seen them around.
Don't be sad if not, I think to build for them maybe a little avatar gallery.
Well, since imageshack or other imagehoster have they limitations its still important to think about the filesize.
I surely think on this many times for example in portable apps or template developing processes.
My personally max. limit of avatars is something around 10kb, its just a fine value and you can add things later