iPhone 5 case by Sensus is touch sensitive on the back, coming in 2013
Yeah, we know that it sounds ridiculous, but just think about it: mobile video games require your finger to touch the screen, which obscures part of the action. That is rarely a problem, but can get annoying on some occasions. With a case like this, gamers will be able to maintain control over the game, all the while having a clear view of the action. In addition, there won't be the need to wipe the screen once you are done playing. The touch-sensitive pads are positioned in a way that should eliminate accidental interactions with the screen.
source: Sensus via Gizmodo