http://www.listia.com/ - Turn clutter into credits. Credits get you things you love!
1) Declutter - Sell the stuff you don't use - from DVDs to clothing to toys, for free!
2) Earn Credits - Rack up credits when others win your auction listings.
3) Reward Yourself - Discover and get stuff you'll love from other members!
http://postcrossing.com - A great place to go to swap postcards with other people internationally for free.
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!