Is it an LED that turns on when the room gets dark? If so...wow, I can't believe the lives that will be changed when people no longer have to stumble into a dark room!
Even better, it's an LED that turns on when the room is brightly lit!
what you need now is stArduino Wars. Orbital death ray, controlled by Arduino. Once you have mastered the LED blink, the next logical step is obviously an orbital death ray.
Couldn't Jesus be considered God's "Hello World!" app? Just sayin....