One of the biggest gripes about smartphones, for all their awesomeness, is battery life. Cho Sinhyung & Jeon Jungjae have released a conceptual design called the "Second Life Mobile Phone Concept" that would give your battery a break with a hybrid screen.
This futuristic looking design employs a full featured AMOLED screen when your phone is active that switches over to an E-Ink display while in standby mode. The semi-transparent screen would also show the battery life percentage remaining. It looks like a fragile little thing, but it's a pretty cool concept that may have its uses in future designs.