VBulletin does have this facility, but I've got it turned off.
Images in the user profile, known as "avatars", tend to be used for cartoon characters rather than pictures of the individual. I don't like them as they just add visual clutter and serve no purpose -- others clearly think they are the best thing since sliced bread!
Jon Fuller's BoatMad forums
have avatars enabled and they seem to be quite popular. Have a look and see what you think -- they could do with some more visitors anyway
If I enable avatars on RIBnet there is no easy way of controlling what pictures people use, so it wouldn't neccessarily have the result that people are asking for. Another option would be for someone to maintain a web page with members pictures -- I would be happy to provide server space for this, but don't have time to administer it.
What do you reckon?