I would have to say my favorite all time addon is between Mobmap and WowEcon

Mobmap is a huge database of quests, items, mobs, all mats for every proffession amongst other stuff.

http://www.mobmap.de/

and wow econ is one that is a full database of ah stuff


http://www.wowecon.com/?l=eJxLtDKyqi...0AHFgXCQ%3D%3D



both are ones I would check out for people looking for such addons.
(though for wow econ it costs like 4$ a month for the full addon but I have found to be worth that for the info it has)