Out next month. Too bad it's not a free app though.

 
To skaters of a certain age, fingerboards (miniature plastic skateboards originally marketed as keychains) evoke memories of countless hours spent doing boardslides on schoolbooks and executing ollies five times the length of the board. Now Illusion Labs has introduced a new iPhone game calledTouch Grind that improves on the concept for the digital age.

http://www.complex.com/blogs/2008/09/11/touch-grind-brings-fingerboarding-to-the-iphone/