I'm using a N800 booting off a mmc, so you probably can't apply this directly, but it might give some ideas.

From time to time I plug in my N800 and write an image of the system partition to disk with a program called dd (diskdump). If something goes terribly wrong, I can just get a new card, partition it, dump the image back and I'm ready to go.

I also have a rsync script, which I can use to copy the contents of my home directory to a computer at home. It works securely over the internet. The script is very simple, but you need ssh and rsync to make it work. I try to run this as often as possible.