The Real Racing series has been one of the most successful and beautiful racing games on iOS Devices since it was released. The sequel, Real Racing 2, was released some time after and it blew the heads off of some bystanders. Developer Firemint and Electronic Arts have released a Mac App Store version of the game with an awesome extra feature. Now if you've been taking advantage of AirPlay or TV-Out then you should already have a feeling of what this new feature is like. You can connect your iDevice via WiFi and use it as a steering wheel for your Mac. Minus a bit of lag, the external controller option is great and gives you the feeling of a real wheel. Unfortunately since you have to do it through Mobile Safari, the iPhone and iPod Touch version will not lock in Landscape mode(which is what you want). You can still play in Landscape, but turning too hard to the right will cause your device to go portrait and might screw you up. There is another way to connect your device without using Mobile Safari, however it doesn't seem to be working as of now. If you have an iPad, the Landscape will lock and you can enjoy the game without any troubles.
Real Racing 2 can be picked up from the Mac App Store for $12.99:
Mac App Store - Real Racing 2