Now as much as I love Star Trek I have to admit that it has unleashed a few very unfortunate things onto this world. It's odd but it seems that appearing as a regular cast member on the show tends to make an actor believe that they can, and should, have a music career. We all know about Shatner's infamous "Rocket Man" and "Lucy In The Sky With Diamonds" covers, but how about "The Ballad Of Bilbo Baggins" from Leonard Nimoy?
Brent Spiner who played Data on Star Trek: The Next Generation released an album called Il' Yellow Eyes Is Back [wp] which included backing vocals from much of his fellow cast. I don't have a clip from that, so count yourself lucky.