Too many of my mac using friends surprise me by not being that hot on backups, having nearly lost my mac to ill-fortune a while back, I take backups more seriously now. However I spent a long time looking for the friction-less way of doing it, trying .Mac Backup and mirroring to local hard disks etc. I've now found what I think is a minimalist, but effective solution. This is one that will get you your important stuff back, but maybe not everything, I'll explain.
I use Strongspace and the recipe for iCal, Transmit and Automator. I then set my Documents folder to mirror sync using an iCal appointment running a script every work day at 11. It is advisable to do the first backup manually, as the script will fail if the sync hits problems. My Documents folder was a few gig and took a good while for the first copy across, but now the sync takes 10-15 minutes.
Strongspace has pretty much always been there when I've needed to sync stuff to it. I know that this is entirely possible using rsync, but iCal is a really friendly way to do this, I can shift a backup if I know I'm going to be busy, or skip them, without editing a script. I no longer need to worry about that part of my backup routine, pictures are next for the strongspace approach. Applications I have disks or can download, music I mostly have on CD, so could re-rip or copy to externals. I'd recommend giving stongspace a try.