There's been a recent explosion in git guis on the mac. I still keep coming back to GitX, specifically BrotherBard's fork:
Recently there have been a lot of new contenders:
- Tower - pretty, nice inline diff viewer, seems like it might be more n00b-oriented, free while in beta.
- GitBox - minimalistic. Also expensive.
- SmartGit - commercial, expensive
- GitMac - looks nice, can't play with it yet.
- SourceTree - does both git and HG. Haven't played with it yet.