Streetlights that adjust their light output according to the phases of the moon — this design idea was the winner of Metropolis Magazine’s Next Generation design awards. These streetlights would have light sensors built into them that are sensitive enough detect the brightness of the moon, and dim themselves accordingly. For example, if there was a full moon with a clear sky, the lights would be dimmed to 10% of their power, whereas a moonless night would mean lights come on at fully intensity. Since the streetlights would also make use of energy efficient LEDs, the combined savings would be 90-95% over a traditional streetlight.
Now attach solar panels to the tops of them and let them charge up all day and you REALLY have a streetlight.