WOWHEAD
MMOCHAMPION
ELITIST JERKS
BATTLE.NET
Wowhead is a GREAT item data base. They are always up-to-date with what is in game and on the beta/PTR. They are the BEST place to get info on any quests you are not sure about or any items you are looking for.
This is where you get all the WoW news, they are on the ball when it comes to releases, patches, and everything Blizzard. Make sure to keep an eye on their homepage!
Looking for some advice on the best way to play your class? This is the place to start! With dedicated people for each class making posts and doing research for the best specs and spell priorities it is a great resource to get you going in the right direction.
This, of course, is where you go for Blizzard products. Upgrade to the newest expansion or buy that new in-game pet that you are seeing everywhere.
MUMBLE
This is what we use to communicate while we play the games we love. It is a great voice client with almost no lag what so ever. Download it and let someone know that you need the log-in info.