I heard the audio of William Shatner's "Rocket Man" years ago, but it wasn't until a few weeks back that I finally saw the video of it. The footage comes from a 1978 sci-fi films awards show. It's grainy but you get the idea.
More recently, Family Guy's Stewie Griffin performed a tribute to Shatner's version in an episode. I hadn't realized that Stewie's performance is a nearly identical parody of Shatner's song until I saw both videos.
Both of these links appeared in Gene Weingarten's chat last month, and I kept forgetting to post them. They're SFW but turn your speakers down a little or plug in your headphones -- both songs start playing as soon as the pages load.