Backup and version control tools are in fact the same : their job is to keep different versions of files. Using git as a backup solution is an interesting point of view for this hip version control tool. If you're interested in start using Git altogether, check out this tutorial.
Update : EigenClass is a git backup implementation in OCaml.
Update2 : an important remark is that Git does not preserve file ownership. This might be a no-go for restore operations, but for personal file backup this might well do the job you're looking for.