Official Links:

Warhammer Online Official Page - The official site for Warhammer Online

Warhammer Herald News -  The Community News and Update center for all things Warhammer.

Mythic - The Creators of DAOC and Warhammer Online.

Customer Support - Official Customer support site. Having Trouble? Look here.

Warhammer Online Account - Your EA/Mythic accounts page for Warhammer Online.

Database / Info Sites:

Wardb.com - An extensive database website for all things Warhammer.

Warhammer Maps - A growing site with maps and useful info.

Ten Ton Hammer - Another "All Things Warhammer" site.  Very well maintained.

Warhammer IGN  Vault - Comprehensive info site.  Well Maintained.

Career Planner - Check out various spec possibilities here!

Warhammer Wiki - Wikipedia for Warhammer

UI Mods and Cool Stuff:

 Curse Gaming Mods - Curse is a famous "MOD" site for many games. Check here for interface and other add-ons.

Class Specific: