Google Ad Game
Google goes a long way to wow the geeks. Not only is there a rumor that they actually bid "pi" billions of dollars and they took other natural constants to determine the right amount of cash for the Nortel patent package, they also created a really addictive game in the tradition of The Incredible Machine to advertise Nexus S and Android in general. The game was certainly cheaper to build than the bidding, but both are really cool.