*dies*
100x100 and 5 colors!!!!

..........that's my format! ......was....
Looks very Trigun-y, besides the fact that he looks like a clown. Amazingly neat and orderly dithering and excelent shadows. The white pixels going down the thin parts of the arm kind of stands out at me though, maybe could go with out them....
The neck is bugging me too; there's the exactly vertical line going through it, and then it almost seems pillow-y on the neck itself.
It's a great start, and gets a thumbs up by me, because of the 100x100x5colors. If you made it for your avatar, why don't you use it for it?
Edit:

6 colors (forgot to count transparency)