There are a lot of options ...
I have been looking into mkCDrec for doing fullback ups. (http://mkcdrec.ota.be/
) I also bought O'Reilly's Unix Backup & Recovery it pointed me to this site (http://www.backupcentral.com/free-backup-software2.html
) There is a lot of software out there so you have to be clear about what you are going to backup. Do you want to be able to do bare-metal restores from you backups or are you just backing up data? What do you want to store you backups on? CD-ROMs, tapes, or hard drives?