While I'm on the retro kick: YouTube turns up trumps with one of my very favouritest Muppet Show song numbers ever-- Harry Belafonte, singing what was then a new number for him, "Turn the World Around," in company with some very beautiful African-mask muppets.
I've always liked the Muppets best when they broke away from the standard Kermit-and-Piggy mode and started pushing the envelope on what they could do with puppetry: "The Dark Crystal" was one of my favourite films as a kid, partly for that reason. I'll see if I can find some more later on.
Plus: I embedded a video! Go me!