Transferslot - Easily buy and sell side-projects
Domainling - Domain search engine
Freemarket - Domain marketplace from Freelancer.com
Mashword - Find a name and register a domain for your business, baby, project, and more. Mashword is a powerful company and human name generator that determines the pronunciations of entered words and then creates unique combinations and variations.
Negotiante - Sell Website for Free
Lean Domain Search - Find a Great Domain Name w/ twitter handle availability