The Million Dollar App is a somewhere between augmented reality, a game engine, an advertising gimmick, an art project, and an homage to the Million Dollar Homepage.
More than just selling and serving ad space in an iOS-native environment, the tileset acts as building blocks for multiple game modules.
You can simply visit different advertisers, see what's new, play new and changing games, or buy pixels yourself through in-app purchases. Pixels you buy become yours, can show what you want and go where you want (within reason) and will show on every other user's version of the app, as long as the app stays around.
Own (or just experience) a unique piece of internet history!