FlyBack is a snapshot-based backup tool based on rsync It creates successive backup directories mirroring the files you wish to backup, but hard-links unchanged files to the previous backup. This prevents wasting disk space while providing you with full access to all your files without any sort of recovery program. If your machine crashes, just move your external drive to your new machine and copy the latest backup using whatever file browser you normally use.
BackerUpper is a tool similar to Apple's TimeMachine. It is intended to create snapshot-backups of selected directories or even your full hard drive. From the BackerUpper project page: "Backerupper is a simple program for backing up selected directories over a local network. Its main intended purpose is backing up a user's personal data." This article shows how to install and use BackerUpper on Ubuntu 7.10 (Gutsy Gibbon).
This document describes how to set up, configure and use Timevault on Ubuntu 7.10. The resulting system provides a powerful backup system for desktop usage. TimeVault is a simple front-end for making snapshots of a set of directories.