Now here's a simple, handy app that, when you think about it, seems surprising that Apple hasn't built it into the Watch by default. It's an app that displays battery level of the iPhone its paired with. That's it. Nothing complicated about it. It's called Power, and it's available now on the App Store for $0.99 from developers Surenix. The other neat part about the app is that it can show when the iPhone is being actively charged, even if it's in another room.