Decimus’ Synk has gotten a major update and now comes in three versions. It can now make encrypted backups (each file individually) and compress archived files. The new ZeroScan feature makes it much faster at determining which files have changed. Instead of scanning the source and destination directories, it observes file system activity in the background, keeping a running list of the changes so that when it’s time to sync it already knows what needs to be done. This is a great idea, although personally I prefer the safety of the slower compare-at-backup-time method.
Right now, I’m using DropDMG for DVD backups, SuperDuper! to maintain a clone, and rsync for syncing with my PowerBook. But, assuming the memory use is now reasonable when syncing lots of files (as was promised for 6.0), I’ll probably find a use for Synk, too.