In conjunction with Nintendo and The Pokemon Company, Gamestop will be holding multiple Pokemon themed promotions this entire month throughout USA, where buying Pokemon themed items from a Gamestop store can enter you into drawings for prizes such as a Pokemon themed Nintendo 3DS XL or a trip to Hawaii (I have no idea what that last one has to do with Pokemon, but okay).
The promotion is known as Pokemon Megastop, and it runs till 11.59PM CT on December 31- a very long time to go get something Pokemon from a Gamestop store. Everyone who buys anything will get at least a code to be entered on the Pokemon.com website, which can be redeemed for a digital booster pack in the Pokemon Online Trading Card game.
Another caveat is that this promotion is only valid in Gamestop stores in the United States- so if you live in Canada or Mexico, sorry.