Your header is boring and flat (more constructive comments inside :))
I had a discussion on IRC about github and bitbucket some time ago, and someone said “you know, github just has something, it just looks better”.
So I thought I’d check if I could find out, why.
The differences aren’t so big: Their newsfeed looks like a real button, the text in the search field does not overlay the icon (looking glass)¹ and their header is fancy (creates an illusion of depth, and it isn’t all the same color -> fixable by making the most relevant buttons (to users) look as if they were sticking out of the mercury background -> make bitbucket the background on which people work).
¹: Just add 4 or 5 spaces before the “Find a project”-Text to fix that whithout taking up real user-typing space.
PS: I Just worked on github, and a feature I really liked are their rich pull-requests: Showing all revisions which will be pulled and allowing comments, like an integrated hg incoming with the option to comment at any point. It’s a new way of contributing, and it gets people to use their site for talking about their contributions.