Amazon is giving away one free Christmas song download a day now through Christmas. They did this last year and I added 25 songs to my Christmas playlist! To view the song for each day visit this Amazon Page. The site states that the songs are only available to download for "a limited time" and I'm not sure if you'll be able to go back and download the songs from previous days.
There is a free Curious George Christmas song from Amazon here as well.
Amazon offers free songs all the time, not just during the Christmas season. It's a good way to hear new music. Who knows, you may find some new favorites!
If you like Christmas music you can tune into 104.3 or 99.7 on the radio, both stations are playing Christmas music full time now. Or if you are near your computer, I highly recommend Pandora. It's like an internet radio station that you program to songs that YOU like. It's great all year round. Listen to only the songs or artists you like!