Two Christian radio stations that I know of offer free new music downloads occasionally on their website--just wanted to share my info with you in case you're looking for a good free download now and then! One is Air1 radio station--their free song is here and the other one is KLOVE and their free song is here . They have new songs every couple of weeks, so check with them periodically!
If you know of any others, feel free to let me/us know! Enjoy!