I use rsync nightly to sync all my data both onto a local backup server and also to another machine hung off a friend's DSL line. I now know that even if my house burns down my data (including 10GB of photos and 20GB of MP3s) is safe.

My remote server is a very cheap mini-itx based machine, so it cost less than a decent tape drive and is completely silent apart from the hard drive (which is important because it has to sit in a friend's house).

I obviously had to connect the remote server locally to do the initial transfer. Rsync then just sends the changes each day.

P.S. I have rsync configured not to duplicate deletes, then if I delete anything locally it doesn't dissappear from the mirrors. Occasionally I it with the delete option so that it cleans up stuff I have moved around.

P.P.S. I wish rsync was just a little bit more clever, so that it noticed when you had moved files and just moved the ones on the target, rather than duplicating them into the new location.