Lots of charities welcome your donations. Groups like Freecycle http://www.freecycle.org/ and Recycler's Exchange http://www.recyclersexchange.com/ exist to help you get rid of useful objects that you just don't want anymore. If you're in a Craigslist City http://www.craigslist.org/about/sites.html , make use of the "free stuff" section. Give away clothes that don't fit, the boxes you used in your last house move, or the scented soaps that don't appeal to your sensibilities.
Make it a rule in your house that nothing useable goes in the trash until you've given the community a fair shot at it.
I know in my area, items that have any use or value that are placed in the alley disappear quickly! Also, you can have a yard sale and even make a little cash!
