FoldersSynchronizer is a nifty and popular utility for Mac OS X and 9 which synchronizes and backs-up files, folders and disks.
FS lets you organize your sync and backup in several sessions to save to a file for a later reuse.
On each session you can apply special options like Timers, Multiple Folders, Filters, Exclude Items, Auto-Mount local and remote volumes, launch your own AppleScripts, set how to resolve conflicts, execute an incremental or an exact copy, include locked files...