I do my backups for my home systems via an online backup over 1024/256 DSL. I currently have 30GB that is protected this way, which works fine because the daily changes to files are rarely more than a couple of hundred MB.

I don't use an online backup service, I have a cheap, quiet Linux box installed on a friend's DSL line and I use a rsync to do the backups at 4am every morning.

I sleep much easier at night now I'm not relying on crappy tape drives (didn't have even DAT) to backup my life's data...

P.S. I'm wishing I had put more than a 120GB disk in the remote Linux box though, as my Canon 10D camera seems to be eating about 1GB of the space a month !