For non-supported games Nyko has prepared a free app called Playground that elegantly allows nearly any game to work with the PlayPad in short order. Some games natively support mapping. For those that don't, Playground will let players snap a screenshot of their game and then drag controller elements onto the picture to create custom mapping. Say you've got an on-screen button in your role-playing game for drinking a potion. Snap a picture, drag one of the controller's face buttons to the area the button appears, and you're good to go.
This look pretty interesting;
http://kotaku.com/5917778/a-controller-solution-that-strikes-at-the-very-core-of-android-tablet-gaming?utm_campaign=socialflow_kotaku_facebook&utm_source=kotaku_facebook&utm_medium=socialflow