Christine Lavin and the Mistletones
A Christmas/Kwanzaa/Solstice/Chanukah/Ramadan/Boxing Day Song
It's an acapella round that gets in all the holidays. It's cute, fun, and my church has replicated it. For a deliberately pluralist faith, it's perfect.
Edit: I had a link up to a "free download" that makes me nervous - sends you to an .exe file.
So, here's the link to it on Amazon. You can play the sample for free and if you like it, download it for .99.