Wowwiki.com is the site I use most often. It's the best source I've found for info on game mechanics, class abilities, and instances, and it has a lot more info on quests (including coordinates) than it used to. I much prefer the site's format to that of Thottbot. Worldofwar.net is another pretty good source for information and add-ons, and declares itself a gold-ad-free site. Have no idea who owns it, though.