I love the song by(I think) the Waitresses. It's like a story/song about the girl spending Christmas alone and she meets a guy in the supermarket and they both forgot cranberries. I know I'm not exlplaining it right, but its very catchy and I love hearing it!
When I was still in school, a very musical family participated in the Christmas Eve Candlelight service at church every year. Once all the candles were lit, the mother would play "Oh Holy Night" on the violin. Oh, was it beautiful!
I also like "In the Bleak Midwinter". If you can't tell, I'm a fan of "Early Music" Christmas music. A great album is Loreena McKennitt's "A Midwinter's Night Dream".
It's an instrumental (though most of the track's on that CD have vocals), but here's McKennitt's redition of "Bleak Midwinter".