So, post your images and perhaps a description of why you chose that particular look. For example; do you always go for the same appearance in all games, or does the game set the theme of the character's traits? Do you make the avatar look like yourself? Preferences on the gender of the character?
I'll start with a couple of mine:
Mass Effect 2:
I always make male characters in games, for Mass Effect, I went for a mixed race character because I figured in the far, spare-faring future, most of the human race would be homogenized to the point of not looking like a single race. I usually try my VERY hardest to make my characters "attractive," as I couldn't find myself playing an ugly character, honestly. Some of the Shepards I see are horrendous looking.
Like this one, click at your own risk!
http://img717.imageshack.us/img717/2641/uglyshep1.jpg
Fallout 3:
I didn't have a particular theme for this character, I just wanted to make a regular-looking guy without any stand-out traits. I was happy with the end result, I usually outfit my characters with facial hair, if I can. Can't stand baby faces.
