Today we're releasing Bitmarkets, a client for private decentralized marketplaces. It's based on Bitcoin two party escrow and uses Bitmessage and Tor for privacy. Open source, free and no fees.

Application, source, white paper and protocol spec available at:

http://voluntary.net/bitmarkets

First version available for Max OS X 10.9 or higher.
Note: This is an early beta. It works but it's not polished. Any feedback would be really helpful.