LBackup

Duplicity (Tutorial - Encrypted Backups)

Link-Backup (intelligently handles renames, moves, and duplicates)

Distributed Internet Backup System

rlbackup (similar to both rsnapshot and LBackup, support hard-linked snapshot file system backups)

Secure Remote Disk (simple user interface for MacFUSE and sshfs)

Rdiff-backup-web (Web front-end to rdiff-backup)

Simply Open Source Links (Bookmark of list various open source projects)

Retrospectiva (Bug Tracking and Collaboration)

FreeNAS

hfstar (HFS aware version of tar)