Off the top of my head, I'd have to say "Nova Radost' Stala," an Eastern European Carol that most Westerners would probably never hear, and Mannheim Steamroller's rendition of "Pat-a-Pan."
I know this may sound strange (literally), but growing up in Southern California, it just isn't the Christmas season until I hear Jose Feliciano sing "Feliz Navidad". Awful I know, but I can't help it, it's such a happy little tune.
@cortezattic: good to hear there is a Polish version of Nova Radost' Stala! The melody is the same, and the Polsih is so close to the Rusyn and Ukrainian I grew up with that I can still understand it! Thanks for posting that!
That brings back great memories of the music that Mom and Dad would play when we were decorating the tree.
Traditional: O Holy Night, Carol of the Bells
Pop: Blue Christmas, basically the whole soundtrack of A Charlie Brown Christmas.
Novelty: Christmas in Hollis, Porky Pig's version of B-b-blue Christmas.
Simon