Forthcoming DS remakes of Pokemon Gold and Silver are to come with a "PokeWalker" peripheral, a pedometer that levels up your Pokemon as you stroll about.
Andriasang has the details and images straight from the Pokemon Company in Japan. The PokeWalker is a cross between a Tamagotchi and the pedometers that ship with DS health software like Walk With Me!
Shaped like a flat Pokeball with a screen, the PokeWalker allows you to transfer one Pokemon at a time to it via infrared, which will then gain experience and affection for you with every step you take.
Blizzard needs to make one of these things for World of Warcraft immediately.
Pokemon Heart Gold and Soul Silver are remakes of the turn-of-the-millennium Game Boy Color originals, Pokemon Gold and Silver, for DS. They'll be released in Japan at the end of this year.