At my previous workplace I tried to introduce something better for code versioning than tarballs or (more often than not) date suffixed folders. We used windows. CLI was just a total no no. Long story short, I tried bunch of GUI tools/plugins. Most tools were either too simple for anything beyond personal repo or graphical git command/switch selector.
Out of everything I tried SmartGit [1] stood out for its power (never had to use shell for about half a year) and still graspable simplicity. IIRC supports custom providers OOB.
[1]: http://www.syntevo.com/smartgit/