The links have been updated to those relevant to post 4.0 WoW.
To try and clean up the stickies a bit I'm going to sticky and lock this post here (idea shamelessly stolen from the Shaman forum). All the raiding guides/compendiums are still here and are linked below. If you feel a topic deserves to be added to this list just send me a PM.
Please post in the linked thread rather than start your own.
MMO-Champion Forum Rules
You should be aware of the forum rules before you post anything. Most of it is common sense, but if you find yourself getting banned for something you didn't think was wrong, 'I didn't know' is not going to help you.
Leveling a Warlock Leveling a Warlock - The Fun Way
This explains not only the best way to level a warlock, but also the alternatives and more. Start here.