To follow on from the Beatles/Stones/Who threads....I've been listening to REM for the first time in years and I'm blown away by how good some of their stuff still sounds. But to pick one song is almost impossible - for me you could pick 4 songs each of Document, Green and Automatic For The People and there would be little to choose from. Plus there's some excellent stuff in their early albums.

I'll narrow it down to 3 and they're fairly predictable:

Man On The Moon
Orange Crush
The One I Love