Would you like to see something more useful on your Android device screen when it's plugged in via USB to your laptop or mains?

How about something like a desk clock?  Well XDA forum member MrMooh has written an apk that does just that.

DeskClockPowerMonitor has been developed so that the service listening for power plugins runs in the background. When launched, the application will try to launch the Android 2.1 clock initially and then the HTC clock when a power supply is connected.

It should start automatically after booting up with a button to manually start or stop the service.

For more information, and to download the latest version of DeskClockPowerMonitor, take a look at the forum thread.