Possibly the best to-do app in terms of user interaction and functionality.

gregmelander:

JUST SWIPE

Clear…it’s a representative of a major leap forward in smartphone app design, as it’s been built from the ground up for the touch interface. The app is based solely on the use of now-common gestures: swipes, pulls and pinches. There are no buttons with Clear, and yet, it’s surprisingly simple to use. In fact, that’s the point. (via Clear: Why This Simple To Do List App Has Everyone Talking | TechCrunch)