What is the LEGO lamp used for?
Many things including: 1) Decoration. 2) Debugging aid. Much like you would use a beep in your program to indicate whether the code actually got to a particular point, you could tell the light to light instead. 3) Used in combination with a light sensor and pulley wheel you can have a makeshift second rotation sensor. 4) Something nobody has thought of, but will revolutionize FLL.
