WoW Insider, did. She's recently conquered getting your computer to display World of Warcraft on one screen and your toolbars on the other, giving you a clear picture of the beauty of Azeroth without all of those clumsy bars.
The only downside to this technique is that the game can really only be rendered on one monitor and not across two full monitors. Rendering across two monitors causes your character, who would be standing in the middle of the two monitors, to be annoyingly split across both of them. Now, if you only had the expensive gaming rig to support those three monitors.