Project: Automated offsite backups for an NSLU2 -- part 1

I have a Linksys NSLU2 on my home network, and I'm very pleased with it. It is almost silent, was not too tricky to set up, cost very little (and is even cheaper on Dabs these days), and it happily serves the contents of a 200Gb USB-connected hard disk to all of my PCs. But there's one problem; it would be easy for someone to steal. I was burgled a couple of years back, and while (thankfully) they missed the disk, I realised that while almost everything else in my flat is insured and replaceable, the data on that drive is not. I decided that I needed it backed up offsite automatically, so that even if my home was completely cleared out, my data at least would be safe.¹

Shortly after the burglary, I set up a temporary solution, which - like all these things - has lasted for somewhat longer than intended. My media-centre PC is always on, and it runs IBackup, which synchronises the contents of the NSLU2 (mapped as several network drives) every night.

This approach has three problems:

• Cost of the service. IBackup charge $10/mo per 5Gb, which isn't bad by the standards of their competition, but is more than I really want to spend - especially given that my usage is getting pretty much near that 5Gb limit now. Costs go up in 5Gb increments.
• Cost of electricity. Leaving a PC on all the time costs more than you'd think. Our electricity bill at work comes to something like GBP 7 -- say, $12 -- per computer per month; domestic electricity is a bit cheaper, but that's still about as expensive as the storage. I don't know what the NSLU2's power requirements are precisely, but it's probably safe to say that it uses less than a full PC... (Update - It looks like it uses about 2.5W - see the table at the bottom of this page -- which is a couple of percent of a PC's power consumption.)
• Elegance. There's just something fundamentally wrong with getting a clever little NAS device to handle all of your shared disk space and then keeping a fully-blown PC running just so that the NAS disks are backed up. The server should handle its own backups - otherwise you might as well just share space out from the PC.

So, I need something better - cheaper, more power-efficient, and more elegant. Here's the plan: I want to find a decent supplier of offsite backup space, and to somehow put in place software to keep the contents of the NSLU2 synchronised with that space. I suspect getting this all sorted may take a while, and I'll keep detailed notes here.

Next: Where and how?