I just came across this remarkable gem - a rendition of 21st Century Schizoid Man
by the Crimson Jazz Trio, with former King Crimson drummer, Ian Wallace on drums. I love it!
I'm also a big fan of Pat Boone's version of Smoke on the Water:
What totally unexpected cover versions have you enjoyed? Not allowed to mention The Flying Lizards's version of Money
because it's too obvious :)