Bonobo Git Server for Windows is a web application you can install on your IIS and easily manage and connect to your git repositories. Go to homepage for release and more info.
AFAIK all data is stored on the file system in the App_Data folder in the website directory (App_Data\repositories for the actual git repositories). These are standard files, so any backup service will work.
Can you give me some solutions on what you use to backup your Bonobo Server and data? If there is a FAQ somewhere, that would be neat.