As a good consumer, my family and I buy lots of stuff. And, we end up with old stuff that we don't need. We've given lots of stuff away over the years, either donating to local charities who need it or giving it to strangers we contact via Craigslist.
I recently discovered Freecycle.org. Their mission is simple. It's a local non-profit network of users who exchange items for free. If you can give away something to someone who needs it, that item will be kept out of the local landfill. Not really recycling, Freecycle is more in the realm of 'reduce and reuse.' By giving away something, you not only keep it from taking up space in the trash, but you also allow someone else to benefit from this item without consuming additional resources to build something new.
Of course, there are lots of ways to swap things on the Web. I recently met the President of Swaptree. Swaptree is nice if you want to get something back when you give away a book, CD, or DVD. But, you have to set it up with what you have an what you want in order for it to figure out what you need to give up to get the item you want.
When you just want to clean out the basement of unused stuff that you would otherwise throw away, try Freecycle.