I've mentioned Kirby Ferguson before. His Everything is a Remix video series points out that there's no such thing as complete originality - everything draws something from stuff that's come before. If you're an artist and you get hung up on thoughts like "I am unoriginal. I suck. Hey, I wonder if I have any email," you should check him out. He'll make you feel better. Anyway. He gave a TED Talk recently. It's very good.