Rdbackup is a small and easy to use backup system based on rsync and ssh. It works with a disk-to-disk backuping strategy where the data are stored on a single backup server. Rdbackup also provides a status monitoring through the SNMP interface.
Tiny linux distro with howto that runs solely on ramdisk, boots from CD, network, or USB, is less than 40MB, and works as a server/router with many different servers (Apache web, ssh, ftp, telnet, etc). Minimalized from Fedora Distribution.