Touch Pilot already has one of these apps available on Google Play which allows you to turn your Android tablet into a gaming control to use with your PC when playing flight games. The company is now planning to release Tilt Racer tomorrow which does pretty much the same thing with your Android device but for PC racing games this time.
Essentially this application will turn your Android device into a steering wheel game controller, allowing you to use it with almost any PC racing game. In order to use this, you will have to download the free server software for your PC from the company's website. Then you just install the Tilt Racer application, tweak the settings to your liking, and then you just use your Android device as a steering wheel.
While the server software is free to download and install, Tilt Racer will be priced at $4.95 when it lands on Google Play tomorrow. You can see this app in action in the video below.
Developer Website: Touch Pilot