git selfupdate
builds a specified version of git and installs the man pages.
It isn't particularly fancy, but it can save some time and effort (especially on the Mac) if you aren't getting Git from your package manager.
$ which git-selfupdate
~/bin/git-selfupdate
$ git selfupdate
Usage: [sudo] git-selfupdate version
$ git selfupdate 1.6.5.1