John Wiegley has released a nice package that can be really helpful if your workflow involves tracking and saving your work with Git. Sometimes you do some work and then decide that you don’t want that change and would like to revert back to what it was. Wiegley’s git-undo makes that easy. You can mark a region and have that region replaced by the working tree or HEAD version of your Git tree. You can also walk back through your Git history undoing previous changes to the region in your Git tree.
It’s not yet in Melpa but it’s a single small file so perhaps Wiegley has no plans to submit it.