Rise
In case you haven't noticed, gestures are starting to replace buttons in simple apps. Rise ($2) is a perfect example. This replacement for Apple's serviceable built-in alarm replaces the bland aesthetic of the stock app with a clean, inviting interface that has you swipe up and down to set the alarm time, swipe right to turn it on, and swipe upwards to choose things like your wakeup sound or playlist. No, it doesn't really do anything else, but that's the point — only by stripping away unnecessary features can you make an app this good looking.