Here is a great site!
www.lala.com
I have hundreds of old cd's, many that I do not listen to. This gives me a way to trade them for something I want.
1) go there, register and list all of the cd's that you want to get rid of.
2) List all of the cd's you are looking for.
lala sends you a packet of mailers and for every cd that you give away, you get one of your needed cd's for a dollar(billed to your credit card).
Its very easy and I have been able to rid myself of a couple of real dogs out of my music collection. Another cool thing is that they give a small amount back to the musicians. Check it out.