I’ve been unloading a ton of old CDs and filling in holes in my collection through a site called Lala.com, a cheap-and-easy CD-trading site. Along the same line as Lala.com is BarterBee.com, which adds games and DVDs to the trading.
The site, instead of just straight trades, lets you assign point totals to the stuff you’re trying to get rid of. Someone then pays you the points you requested and you ship out the product to the buyer using your own envelopes or those provided by the site. You can then use the points you collected towards purchases of anything on BarterBee. However, when you buy something there’s a $1 charge made to your account (yep, you have to keep a credit card on file that they bill upon purchase of points, envelopes, or accepting an item you requested).
If it sounds like something you’d be interested in, you can sign up and get a free purchase ($1 and 5 points, which is enough to get a free CD).
BarterBee.com [web site]