There’s a pretty funny (but over and closed) mash-up contest here.
Some of my faves:
- 20,000 Leagues Under the Sea and Cake
- At Play in the Magnetic Fields of the Lord
- A Kraftwerk Orange
- The Maltese Falco
- Mein Camper Van Beethoven
- The Chemical Brothers Karamazov
(via, who has a few suggestions of his own)