Set custom avatars for users with no Gravatar. The avatar will be the first (or any other) letter of user's name on a colorful background.
A WordPress-BuddyPress plugin to set fancy custom avatars for users with no Gravatar and no profile picture.
Change avatar sad wordpress by other coquette
Simple jQuery plugin to make gmail like text avatars for profile pictures. These avatars can be scaled up to any size as they are SVG based.