I bought a 1.5 TB USB drive recently, because it was clear that I needed a place to store my growing stash of video and photos. The photos have the triple backup strategy, on my computer, my Time Machine drive and in the cloud on Amazon S3.
Video is more tricky because it's so big. I can't realistically keep all of the original files, so I've resorted to making high quality compressed files for the edits, and those get backed up to the Time Machine, but not S3. If the pricing comes down, I may change that eventually, but at $0.15 per gig per month, I'm not quite ready for that.
Being a digital pack rat is hard. But hey, it's better than dealing with huge volumes of photo albums and video tape, that's for sure!