@RosanneCash brought to my attention CD Sweep. According to Billboard Biz, CD Sweep founder Jason Roth got an idea from iPodmeister, which sends you an iPod, iPhone, etc in return for your old CD's. His son was diagnosed with Aspergers Syndrome last year, leading Roth to come up with idea to donate the proceeds of old CD's to The Autism Science Foundation, which conducts innovative autism research and supports the needs of people with autism and their families.
It's almost too simple. You let CD Sweep know how many CD's you want to send them. They send you a prepaid Fed Ex shipping label. He's the cherry on the sundae: they will also digitized your CD's and send them back on a DVD as MP3s for free. Whew. What a wonderful idea come to life. Start packing up those old CD's this weekend.