BrandHunt V2 - Search/track domain & social media handles in real time.
BrandBucket - The original marketplace for business names and creative domain names.
Lean Domain Search - Find a Great Domain Name w/ twitter handle availability
Zlipa - Startup names with available dotcoms and logos
NameMing - Get smart domain name suggestions using synonyms, suffixes, prefixes, short url, new gtlds to find the perfect domain name. Generate ideas for social user names and check availability for free!
Brandroot - Great Names for Great Ideas