I know I left out Watching TV (with Roger Waters) because there was only room for 10 entries, but you can vote for it as a "write-in candidate" - just say so in your reply to this post. Here it is if you haven't heard it: [ame]http://www.youtube.com/watch?v=2ik6T-oWoXM[/ame]
I also left out
- Garden Party (with John Fogerty and Timothy B. Schmit) because that's three singers, not two
- Bein' Green (with Kermit the Frog) because Kermit only sings on, like, two lines
Does anyone know of any others I've missed?