There have been many very beautiful, interesting, thought-provoking, or funny avatars on this forum, but the one that sticks out in my mind right now is Jack Flak's current avatar simply because I think it suits him so well.
awesomecakes's avatars are usually cool, I like how she changes them almost everyday.
Negative's one is cool.
CC's. I like when people use pictures of themselves for their avi, but I probably wouldn't do it myself.
Whoever has the "Make awkward sexual advances not war", like that one.
I like booyalab's new one. It looks like her, and she's smiling. Usehername's too.. I guess the trend is to find a celebrity that looks like you to use?