DomainWatch - Domain Monitoring Made Easy
Dictionary Domains - Unregistered dictionary word domains for your side project
Undeveloped - Domains you never thought were available
Domainz.io - Premium domains, for not so premium prices
dofo.com - Domain search platform Dofo.com gathers all registered (350 million) domains of the world in a single place. Dofo also brings together all the domain names that are on sale, provides useful features, all completely free.
domdb - Park your domain in less than 15 seconds