git-guilt is neat; please upstream it it into git. :)
Thanks! I'd have to spend a lot of time dusting off my C skills before considering contributing to git core. If enough people find it useful it's always a possibility.
But some standard git commands are supposedly just shell scripts, like, oh, git rebase.
True, I built it in JS for the library support, but there's no reason I couldn't rewrite essentially the same thing as a shell script.