Recently I tried TortoiseGit, a TortoiseSVN style Git client, however there were no binaries for my 64 bit windows machine. The 32 bit version found on the official site would install, but the shell extension unfortunately does not work.
So I took the law into my own hands and went and built my own version.
So here is TortoiseGIT 0.3.3.0 (64 bit) built from revision 9d3351f627b26d9555794e785cf8bbae22155f12. There is now a newer offical version available at: http://code.google.com/p/tortoisegit/downloads/list
Hopefully 64bit builds will be available from the official site in the future.
Disclaimer, I haven’t fully tested this app, and I suspect some features of the 64 bit build might be broken. Regardless I’ve been able to use at least the basic features of this version.