I haven't looked at Crashplan in detail yet, though one of my co-workers uses it for his Macs and is happy with it.
A quick Google search gives me the feeling that it runs under FreeBSD's Linux emulation and the port seems to break occasionally. I could run it on a real Linux in a VM on FreeBSD though, so that's a potential option.
I use CrashPlan on Linux, Windows, and Mac OS X. Works great for me. Saved my bacon a few times (e.g. accidentally deleting my wedding photos, tax information, etc.). Worth checking out.
(Disclosure: I'm a paying customer of CrashPlan, but otherwise have no connection with the service.)
