Lots of users don't have Gravatars right now, that's because we don't get e-mail addresses from the Github API for some (I'm not sure, but I think that's some kind of option you can set). A user should be able to fix that by setting his e-mail address, and we'll only use it to create the Gravatar hash.

I think it would be cool if the user can update her email address from the profile page (http://codebrawl.com/users/jeffkreeftmeijer is mine) using some kind of in-place-editing thing. :)