Source: http://lifehacker.com/5620838/create-synchronicity-is-a-tiny-portable-backup-and-sync-utility
Windows only: Portable, open-source backup utility Create Synchronicity is a tiny but powerful way to run backups or synchronize folders on your system, an external drive, or to another PC on your network.
Once you've launched the utility, you'll need to click on the New Profile icon and type in a name for the profile, which will open up the settings window where you can choose the source and destination folders and choose the other options you might want. Once you're done, you can easily run the backup profile, or setup scheduling options to happen automatically. Create Synchronicity is free and open source, works on Windows systems only.