As an avid snow-boarder, one of the games I found really interesting from the marketplace is iStunt2, an xbox live game developed by MiniClip games, this snowboarding fun addictive game is a must have.
Play as the Tony Hawk looking dude and board your way through hills, gravity/anti-gravity trails, rails and dodge obstacles too, you control your character by tilting the phone and also tapping the screen to stop, bend down or jump...
You can also do stunts (obviously given the name of the game is "istunt"), try to gain speed so you can be in the air as long as possible when you go over cliffs, this gives you more time to perform different tricks, tricks like 180degrees flips, holding your board either at the front or back, these stunts award you points so be sure to do as much as possible
Here's a demo...
If you love fast paced games, with multiple control methods (tilt + touch) and 100% focus then iStunt 2 is for you.
Get iStunt 2 from the marketplace for $2.99 HERE