http://8bit ch ristmas.com/ (remove the spaces, CAA keeps censoring it)
I just ordered that album, and there are two others (8-bit Jesus, and another one I forgot the name of) that I downloaded a couple days ago. They're all pretty interesting, in my opinion. The one I linked to is the only one you can't get for free, but the money goes to support Child's Play, which is a charity started by the guys of the Penny Arcade webcomic to provide entertainment to hospitalized children. You can get the physical CD for $10 or get it digitally for $4.
Each of the tracks is a Christmas Carol blended with a old video game (I want to say NES but I'm not sure if all of them are NES or not) song to make the 8-bit remix. So far, I've thought every song through track 10 is good (you can stream it on their website), and I'm sure I'll like the final few tracks as well.