As an enormous David Bowie fan, everyone is always asking me if I've heard "Bowie's in Space" by Flight of the Conchords, and yes, I have, but I didn't think it was all that clever. I actually have the same objection to it that I had to Being John Malkovich,which is that you could just dump any celebrity in and repeat their name over and over and over. Being John Malkovich could just have easily been Being Kevin Bacon, or Being Bobbie De Niro, because there's nothing of who Malkovich is as a person in the role as written.
"What you doing out there, man? That's pretty freaky, Bowie. Isn't it cold out in space, Bowie?" just doesn't have any real cleverness to it. A passable Bowie impression with stupid lyrics. By contrast, Sifl and Olly's Olly Moondust skit is just spot on perfect parody. "I dreamt of a wizard with a hot quitar. The lovliest magic man, now he's a star. I got three-D stereophonic laser love. You're on my TV. I've been stuck in space for such a long time. Sorry man, I'm five years late for tea time. Hydroplaning towards infinity. Just some drag queens and me. You dirty little thing..." This could almost have been written by Bowie himself, circa 1972. But don't take my word for it. Compare them for yourself:
Update: Jimmy Fallon's TeBowie is pretty good too: