After moving recently, I realized that we have a lot of CDs and DVDs. They take up a lot of space, and I wanted to really de-clutter and simplify my life. I went through all my CDs and figured out which ones I like, and which ones I didn't. The ones I liked, I uploaded to my computer for my iPhone to download. Now I have a bunch of CDs (both like and dislike) that take up space, and I'll probably never play again.
We tried to sell many of them at our garage sale before moving, but we still had a lot left over. There aren't many local stores that buy back most of the CDs (more selective on titles).
While searching online, I found a company called SecondSpin.com that pays you cash for your used CDs and DVDs. All you do is type in the UPC code of each CD, and it gives you the price it will pay you. I averaged about $1 per CD (range is about $0.05 to $3.00) and mailed a large box to their facility for processing. Count how many CDs you have, then do the math...
Not only do you get to get rid of things you don't want, you make some money in the process, and your item gets reused by someone who wants it!
Give it a try at their website SecondSpin.com.
Update 2/4/10 - I received my check today for $170 (I sent 133 CDs to them). They rejected some of my CDs for water damage, but overall I think it was worth the money and effort.