PSA: with CrashPlan, you can simultaneously backup to your own server(s) or external hard drives right alongside their service. You can also backup to a friend's computer (this was actually their original business model--P2P backup).
Clarification: you can back up to your own servers iff said servers are also running Crashplan. What you can't do, unfortunately, is back up to an ordinary shared folder.
Further clarification: this is correct, but (if someone is reading this and thinking about doing it), you can install the free version of CrashPlan and it works just fine as a backup server.
It's kind of a ram hog, though.
I'd love to use CrashPlan for the bulk of my older projects but I have 350GB data and as I'm from the UK there is no way to seed it. It would take me something like a month to upload all that data.
What's the big deal? Once it's done - it's done. Unless you're on a metered data-plan, I don't see that initial upload as a huge problem assuming you can keep your system alive for the month it takes to perform the initial upload.