Lean Domain Search - Find a Great Domain Name w/ twitter handle availability
Domainr - Domainr
Instant Domain Search - Search domain names instantly by showing results as you type.
BrandHunt V2 - Search/track domain & social media handles in real time.
GoDaddy - GoDaddy makes registering Domain Names fast, simple, and affordable. Find out why so many business owners chose GoDaddy to be their Domain Name Registrar.
Domainling - Domain search engine