PatchKeeper (pk) is an alternative Git command-line interface, with first-class support for managing patches.
If you like the workflow provided by tools like Mercurial Queues (mq) and are looking for something similar but for git, then PatchKeeper might be for you.
PatchKeeper is just a front-end for various (sometimes semi-complicated sequence of) git commands. It operates on normal git repositories, and the managed patches are normal git commits. It can therefore be used either as a replacement of, or as a compliment to, the git(1) command.