This one is a little bit off-center, but SO is probably the best forum for getting a straight answer.
I'm aware of the WoW add-on programming community, but what I can find no documentation on is any API for accessing WoW's databases from the web. I see third-party sites like WoWHeroes.com and Wowhead use game data (item and character databases,) so I know it's possible. But, I can't figure out where to begin. Is there a web service I can use or are they doing some sort of under-the-hood work that requires running the WoW client in their server environment?