Startname - link popularity, bulk whois, domain monitoring, registration, expiring domains, drop catchers, domain name forums, buying / selling domain names.
Midano.com - Complete domain name resources
Aviva Directory - How to get started as a domainer
Tool url - Domain name and url tools for SEO specialist and webmaster
DN List - Domain Name and Website Development Directory
Igoldrush - Internet Goldrush Domain Name
NameNewbie.com - Guide to Making Money With Domain Names
ClickMojo! - Promotion strategies and traffic tips.
Domain name lawyers - Domain Name Litigation, Domain Investments, Trademark Protection, UDRP
Fabulous research - Research about the domain names industry

Domain mart - Selection of both empiric and academic resources for Domainers (not updated anymore)
DomainFood.com - portal for domain business information (not updated anymore)

Other tools and links for domainers >>