Double Dee and Steinski's "The Lesson," created in the early 1980s by two hobbyist DJs, sampled countless unauthorized sources (by dual cassette decks!) to create something innovative and new. Of course, the three songs were never made commercially-available because clearing the samples would have been impossible.Link Discuss
"The Lesson" later inspired an entire genre of cut-and-paste turntablists, from DJ Shadow and Cut Chemist to basement "mash-up" makers. Previously available only by bootleg, you can download the MP3s here. Like Ryan said in the thread, "Long live open source culture!"
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.