SparkleShare is a git-based dropbox-clone, I think it suits your needs.
SparkleShare creates a special folder on your computer. You can add remotely hosted folders (or "projects") to this folder. These projects will be automatically kept in sync with both the host and all of your peers when someone adds, removes or edits a file.
...here's a few examples of what it does well and less well with smiley faces:
###Great
- Frequently changing project files, like text, office documents, and images
- Tracking and syncing files edited by multiple people
- Reverting a file to any point in its history
- Preventing spying on your files on the server using encryption
###Not so great
- Full computer backups
- Storing your photo or music collection
- Large binary files that change often, like video editing projects...
Update (November 2015): The project seems to be abandoned (last release from April 2014).
