Personally my favourite has to be Deja moo's current one - "boo".
I like Sudeep\Nikhil's thingies too, and I admire the courage of anyone willing to put a picture of themselves up there (especially Neil's rather bizarre house-play, not to menion Andre's somewhat dated hairstyle - even if he does have Jacques Rudolph beside him).
Anyone who is summed-up by their avatar (eg ReallyCrazy's pic of Ganguly, Rich's of Allan Donald\Kristen) is also a good idea.
Mine, of course, is simply a celebration of a cherished institution.
One final question: who is the picture of in Sam's Avatar?