bdmn is client/server-oriented backup system. The daemon runs on the machine being backed up, and the client runs on the machine that stores the backup. It is very simple, but very fast. It only uses tar, gzip, uuencode, and Perl, so it is portable to many operating systems. It includes a very simple access control system for itself.
rsyncbackup is a handy tool for scheduled backups using rsync. rsyncbackup lets you easily setup multiple source folders and destinations, both locally, on your iPod or external firewire disk, or at a remote destination using ssh. rsyncbackup has no GUI, but is based on editing configuration files. The script is meant to be run in a crontab, so user interaction is not neccesary. Basic terminal skills are required to use the program.