Blizzard's own Rob Pardo recently dropped something of a bombshell about World of Warcraft at the Paris GDC event when he revealed in a keynote that the game was originally planned as a free-to-play experience. He also adds that, "We didn't want to charge a subscription, but as we researched market conditions, we realized that wouldn't support us." Pardo also discussed how Blizzard drove into the MMO genre in astonishingly tongue-in-cheek fashion: "Very naively, or else we might not have done it." The notion of a free-to-play World of Warcraft makes us wonder just how the game would have panned out had Blizzard stuck to their original plan. Might MMOs have become as big a business as they are nowadays? Who knows, but it's fun to think about the possibilities nonetheless.
You can find the rest of Pardo's discussions within Gamasutra's website. He discussses everything under the sun in relation to Blizzard. Multiple franchises, the Activivision-Blizzard merger and making communties for games are just a few of the many topics covered.