I have two:
Vince Guaraldi Trio - Christmas Time Is Here
John Lennon - Happy Xmas (War Is Over)
And although it's not really considered a Christmas song, Jeff Buckley's "Hallelujah" is too good.
"I like refried beans. That's why I want to try fried beans, because maybe they're just as good, and we're just wasting time." - Mitch Hedberg (1968-2005)
"Football is about if you want to run and fight for each other, if you really want to play that killer ball." - Robin van Persie, Arsenal FC