If you've never played Warioware: Touched, you have to try it. It's like crack, only without the shakes. It's a ton of mini-games that use the stylus. In some levels you even have to blow into the microphone in some games.
The one where I have to unroll the toilet paper as fast as possible is killing me because sometimes the roll gets too big!
The DDRMAX2 game that Gordon got for me for xmas came yesterday. With it was another game (the name escapes me), but you basically start out with a small ball and roll over things to pick them up. Eventually, the ball gets big enough to roll over large items like buildings and small islands.
I haven't played it yet, but Ian says it's a great game and addictive as hell.
^Katamari. It's crazy addictive. It has the most surreal story line and graphics too. Bold colors and stuff that is just absurd. You'll love it.