They had diffs for typefaces at some point: http://i.liketightpants.net/and/how-it-has-come-about-that-c...

I originally suggested it to them, and was kind of sad that they did away with this feature—that being said, it makes sense they want to streamline their platform.

Then, I’ve found it hard to create these kind of things myself, selfhostable FOSS solutions like Gitorious don’t offer enough possibilites to build upon (no real API)