Create Synchronicity – Open Source Backup and Synchronization
http://synchronicity.sourceforge.net/

Create Synchronicity is a powerful and lightweight open source backup and synchronization program, available in many languages. Create Synchronicity is especially light: zipped, it weights about 120kB (that’s 20 times less than an average MP3 file). It makes the backup process extremely easy, while remainining fully customizable. This has been added to the tools section of Research Resources Subject Tracer™ Information Blog.