Part of why moving my office out of the dining room took so long was that there was so much stuff. I took some time to sort through it, and shredded a lot of old documents for recycling and threw away some useless crud. But the best way I've found to get rid of stuff I don't use is Freecycle. It's kind of like a local eBay, but free. You post what you've got, and other people claim it. Or you ask for stuff you need, and people may have it. It's a great way to keep stuff out of the landfill while simultaneously preventing more stuff from being made to replace it. There are now happy new owners of computer speakers, unused printer cartridges from Camron-Stanford House for a printer they no longer have, and some other bits and pieces are awaiting pickup. And I now have a futon for visitors to sit on, and which can serve as a guest bed.
Not surprisingly, I first read about Freecycle over on Treehugger, which is a great site for keeping up with what's new in the world of green and greenish things.