DomainWatch - Domain Monitoring Made Easy
Expired Domains - Information about Expired Domain Names. Check the Availability of thousands of Expired Domains every day before they Drop and after. Just pick what you like!
Domainz.io - Premium domains, for not so premium prices
Domcop - Domcop allows you to find 2million+ expired domains and all of its pat information.
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.
Spamzilla - Spamzilla is a prevailing software for detecting many types of SEO spam automatically.