Years ago, I was shown half.com, a great website where you could buy used stuff cheap, and (thank God) sell it as well. I can't even begin to tell you how much money I've made on there, because a few years ago, they went into business with eBay (You may have heard of it), and I was able to combine accounts and feedback and have now amassed a respectable rating of 856 between the two sites (not bad for a guy who just sells his crap). These places literally changed my life, because now I buy things usually without regret, secure with the knowledge that I can sell it back on one of them if I so choose (this may also be one of the reasons for my enormous debt, but, y'know, the internets giveth and the internets taketh away).
Always remaining on the cuttering edge, I have now discovered swaptree.com, a site similar to half.com, but no money changes hands (except for postage). Only items are exchanged between teh parties. All swaptree does is facilitate the trade by putting the parties in touch with one another. And like half.com and eBay, all you have to do is put in the ISBN or UPC symbol and they take care of teh rest. And you can even import your amazon wishlist into swaptree so they know what you want and can tell you if there's a trade available.
For example, I had two copies of Serenity on DVD (the special edition, and the DELUXE EDITION, or something), and certainly didn't need both. So, I listed and instantaneously was given several options that I could trade it for. I opted for Team America: World Police. I was told who to ship it to and when (which I did), and a few days later, I received my movie. So, now two people with extra crap lying around now have different crap.
The most popular items seem to be books, but there's also plenty of DVD's and CD's (probably because people just copy them and don't need them, but I'm not into that. I like my cover art.), as well as games, but those seem to be rare, probably because there's still a market for them where you can get real money for selling instead of just trading it. Books, on the otehr hand, people seem to have plenty of, and people don't seem to want them after they've read them.
So, that's my plug for swaptree. It won't exactly help you get rid of stuff, but you can definitely swap some trash for treasure on there.