One of the most impressive stats is that more than 100,000,000 (One hundred million) people have played WoW to date. That's impressive by anyone's standards (except for the unimpressible zhanglao, who mentioned that League of Legends currently sees 12 million players daily). Anyways... check it out:

http://media.wow-europe.com/infographic/en/world-of-warcraft-infographic.html