YouTube - "Little Drummer Boy", David Bowie and Bing Crosby Can't beat a crooner and Bowie.

YouTube - Last Christmas - Wham! (HQ Audio) Still the best version

YouTube - Happy Christmas (War Is Over) Prefer Neil Diamond's version but there are no good version of Niels on Youtube

YouTube - Dido - Christmas Day Nice song and the singing is gorgeous.

I also love Carol of the Bells, We Three Kings, O Holy Night, Christmas Rock, and the Nightmare Before Christmas Soundtrack... Yes it counts.