Several months ago, I spent an afternoon tinkering with rsync so that I could back up my Powerbook to my web server over SSH and vice versa. Got it working perfectly...or so I thought. The other day, I actually took the time to look at what was actually being backed up. The web server --> Powerbook backup was fine, but the Powerbook --> web server was trying to backup everything from August 2004 to the present. When I looked on the web server, sure enough, nothing had been backed up for months. After a few moments of panic, I found out I'd been using the "-n" option while doing the Powerbook backup:
-n, show what would have been transferred
So it looked like it had been working, but actually hadn't been doing anything. Anyway, all the files on my Powerbook are now whizzing their way to the web server and I shall once more be properly backed up. (You do back your files up, yes? You're not waiting until you lose everything to find religion, are you? If so, I say unto you: back thy stuff up now!)