I've just uploaded a new tool, git snapshot, which lets you routinely capture snapshots of your working directory, and records them in parallel to your explicitly recorded history.
The snapshot revisions stay out of the way for the most part, but if you need to view them you can look at them, for example using gitx refs/snapshots/HEAD
For me this is primarily useful when I'm sketching out a new project and forgetting to commit anything. When working on a large patch I usually use git commit -a --amend -C HEAD fairly often, which in conjunction with git reflog provides similar safety. However, git snapshot is designed to work well in either scenario.
I have a crontab set up to use mdfind so that all directories with the red label are snapshotted once an hour.