It can keep track of where your repositories are located, and can also be used to tag the various repositories. You can then run a git command across all of these repositories (or based on a tag).
One way I have been using that is to create a tag per project, so across a project which may have many repositories, I can see my git status across all of those by executing:
gr @project status
It can also run normal shell commands as well
gr @project cat package.json
One thing I realised it didn't do in my git bash shell, was run my aliases that I tend to use (e.g. I have a complicated bash alias for a git log command). But luckily someone else has already got an open pull request to fix this (at least for bash), which suited my needs. Yay for open source!
Try it out and let me know what you think :)