http://www.listia.com/ - Turn clutter into credits. Credits get you things you love!
1) Give and Get - Sell your unwanted items and get things you love in return.
2) Discover - See what you can get on Listia with Ink.
3) Earn More - Rack up more Ink for every item you sell
http://postcrossing.com - A great place to go to swap postcards with other people internationally for free. Postcrossing is a project that allows you to send postcards and receive postcards back from random people around the world. That's real postcards! Not electronic postcards.
Paper Back Swap. Swap PaperBack books with other members of the PaperBack Book Swap Club on line. I LOVE this place! http://www.paperbackswap.com . This used to be free. Now I think it costs about 50 cents for each swap.
Swap a DVD - Swap DVD's with other Club members and get movies and such mailed directly to you!
Swap.com is where more than 500,000 swappers worldwide are turning what they have into what they want, with more than 1.5 million items available for swapping!
http://peaceloveswap.com/ - Since 2009 peace. love. swap. organizers have produced over 150 swap events, donated over 125,000 baby, kid & maternity items to charity, and swapped over 185,000 items.The peace. love. swap. mission: to keep gently used baby, kid and maternity items out of landfills, and to donate to local charities, by producing fun and affordable family friendly swaps on a regular basis.
I used to use this, but it's gone now. So sad.... swaptreasures.com - SwapTreasures, a bartering site where everything was free and you could get some cool stuff using points without spending any money. This was their moto: Give away things you no longer need and get things you want for free!