"Peace on Earth/The Little Drummer Boy," Bing Crosby and David Bowie (RCA)

The very fact that Bing and Bowie sang a duet at any time for any reason was a real thigh-slapper in 1977, which is why this performance from Bing's last Christmas special was widely bootlegged for about five years before RCA finally said "the hell with it" and put it out. It's a nice record, too, combining the best aspects of both singers in a performance that is emotional but not at all overwrought or sappy. It's a little difficult to shake loose a copy lately, as the CD single pictured here is out of print, as are nearly all the various compilations that have featured the song over the years.