Make your own Christmas song online and even pick your own instruments.  This is awesome and fun.

Moo.com just put up an interactive game where you can make your own funky Christmas music.  Just click on pictures that represent different instruments and every time you click the picture, you add or take away an instrument.  It's really fun to play around with.

There are 20 instruments to choose from and hundreds of different musical configurations.  It's addicting!