Disk failure (with some data loss)

My primary disk just failed yesterday evening (around 21:30), so I lost at least all data from this week (last backup is from Sunday, 19:00.) However, I think I didn’t miss any unread e-mails, but of course I cannot check as all mails from this week are definitely lost. In case there was something urgent, please send me a mail again.

I ordered a new hard disk which should arrive early next week. I hope to be back up (no pun intended) & running around Thursday again. As soon as the RMA for the faulty disk finishes, I’ll plug it in for daily backups. While I’m at this: What’s your backup strategy?

Here I have one additional internal HDD which I use for backups once a week. I don’t have a “disaster” backup yet at a secondary location; I wonder how well Amazon S3 would be suited for something like this (or SkyDrive.) I’m also planning to install a NAS in my home network and use this for backups, but I haven’t found a nice and free backup software yet. Second problem with the NAS is how to backup the NAS, in case of failure (RAID-5 might be a solution, but how to guarantee that I can rebuild the RAID-5 in 4 years, or, worse, in case the controller fails and can’t be replaced?) I’m curious to hear what backup strategies you employ, and how you coped with disk failures so far.