WoW - Statistics @ Official Site

Blizzard has added a Game Statistics page to the official World of Warcraft site.

This page provides you with up-to-date statistics about some of the most important aspects of World of Warcraft: most sought-after items in the Auction House, most common player-created items, the fiercest killers in the NPC kingdom, most gathered and found items, most looted items, and the most popular quests.