I just use SpiderOak. It includes my dot files during its normal backup routine, it has file revisioning included, and all my files are available immediately upon installing SpiderOak to a new computer.
Personally, I just backup my dotfiles via FTP as they don't change very often, but I lot of my fellow Arch Linux users seem to like backing up their dotfiles to Github. I have never used GitHub myself but everyone seems happy with it.