In Japan, with the release of Nintendogs, half a million DS units were sold, along with the game. In America, the audience is different, and even though Nintendogs is bound to sell a lot here as well, it won't be the DS's killer app. What do you think will be the killer app for the DS? Animal Crossing DS with its online play that AC fans have been dreaming about? Or maybe Mario Kart with 4 player online mayhem along with retro courses? Or maybe even a future game, like Zelda DS? Discuss.