Listings containing free items can be found on Freecycle.org. The Freecycle Network is a nonprofit organization made up of people dedicated to giving away and getting free things to keep them out of landfills.
Joining The Freecycle Network is completely free. To post an offer or a wanted item, click the My Posts tab on the organization's homepage, and then click the Make a New Post tab. From there, choose either Offer or Wanted. Once a transaction is complete, the post should be marked Received or Taken. Information on the history of The Freecycle Network and about volunteering is available on Freecycle.org.