This screensaver on the NTT DoCoMo N702is cellphone looks and acts just like a glass of water. When you move it around, the motion sensor detects your angle and sloshes the water to the left or right, depending. The actual water level itself is indicative of the amount of battery you have left, so it's probably more fun to keep your phone charged up. Maybe some developer can whip up a J2ME version of this app?
An Interesting Way of Showing Battery Status [Slashphone]