DomainWatch - Domain Monitoring Made Easy
Domainz.io - Premium domains, for not so premium prices
Undeveloped - Domains you never thought were available
Picnic - The fastest, cheapest way to launch a new one-page website
Newsy - Monetize your un-used domains and turn them into your own content aggregator with 0 code!
NameQL - Fast and friendly way to find a usable name for your idea, app or business