I know that the topic of avatars has been discussed already, and really, I can't see at all how it could work. We have an enormous amount of users, from a huge amount of cultures. Some users might react to someone's avatar in ways that would damage the community's ability to work together. Throwing in someone's personal identity into every post is asking for trouble. Most users are anonymous, and people like this. And some users are minors. How would we manage if all our younger admins/bureaucrats/developers/editors had their face attached to their comments? I don't even know if it would be legal. Loads of older users would immediately start behaving differently toward them. And what of our many users who don't look, say, respectable, to certain other users? We have enough drama as it is. Please don't add to it by attaching bad first impressions set by whatever prejudices users inherit from the cultures they come from.
Having no significantly visible external identity is kind of important for Wikimedians to work together. In some communities, personal stuff is actively repressed. On the English Wiktionary, userboxes are prohibited. I wouldn't be surprised if some communities banned mentioning one's real name. Anonymity is valuable, and the fact that currently barely anyone knows each other's names or genders is a plus. Avatars would throw all that away, and for what? What's the potential benefit?