General Information
http://www.worldofwarcraft.com - The American home site of WoW.
http://www.wow-europe.com/en/index.xml - The European home site of WoW.
http://wowarmory.com - The American WoW Armory.
http://eu.wowarmory.com/ - The European WoW Armory.
http://www.wowwiki.com - An extremely useful resource. It's user-run, but all of the information on here is completely correct. Gives lots of information about lore, general information on classes.
http://www.wowhead.com/ - Like Thottbot, but without the suck. Definitely the best WoW information site out there.
http://worldofraids.com/ - Lots of information about WoW, and it also provides information about raid encounters and what's been going on in WoW that the main site doesn't make so public.
Specific Information
http://www.wowwiki.com/Daily_Quests - Explanation of all daily quests, their rewards, and how and where to do them.
http://www.wow-pro.com/node/599 - Jame's Free Alliance Levelling Guide
http://www.wow-pro.com/leveling_guides/james_horde_leveling_guide - Jame's Free Horde Levelling Guide
http://tinyurl.com/3dc2g5 - 1-300 Powerlevelling guide for all professions.
http://petopia.brashendeavors.net/ - Complete guide on all information about Hunter pets.
Addon Information
http://wow.curse.com - Huge site of addons, giving you everything you need to customize your UI just the way you like it.
http://wow.curse.com/downloads/details/3459/ - My personal favorite UI setup.
http://files.wowace.com/ - Addon site.
More to come and stuff.