The Swap-O-Matic is a Brooklyn-based art project designed to "remind us that reusing and recycling can be just as fun as buying something new." It works on a credit system — donating an item earns you a credit, receiving an item costs you a credit, and swapping is credit-neutral. Swapping is done by removing an item, replacing it with yours, and then entering your email address for confirmation.
The Swap-O-Matic has been installed throughout the borough, notably at the Lower East Side Girl's Club and Blue Stocking's Cafe. It's a cool idea but I'd imagine a lot of items get replaced with stacks of newspaper almost immediately. [Swap-O-Matic via Laughing Squid]