Warhammer Alliance - As official as the forums get. Also home of some grade A whining.

Warhammer Database - A growiing list of quests and items. Handy if you can't find that last NPC hiding behind a tree somewhere, though as with all user created sites it's not always terribly accurate.
Also home to some excellent online character builder tools - from that link, go to tools then career builder and pick the relevant class. There is a renown builder as well.