If you're working on that Loremaster achievement, WoWHead has added a new wrinkle to the WoWHead Profiler that absolutely rocks - namely, you can see any quests you have yet to complete, in any zone.
However, Admiral Akbarr says it's a trap! And it is, to an extent, because it forces you to get a WoWHead account to install and run the WoWHead client, so they get all that nommy in-game data, and that makes WoWHead even MORE accurate! The bastards!
So, you make the call. I've been running the client for quite some time now. It's unobtrusive, and it's nice to contribute to a database which I use so extensively.
Our GM spent weeks brute-forcing the achievement, and got it mere days ago. I'm staying low for a while.