Here's one to keep the greenies and the amateur astronomers happy. Civil Twilight, a design collective based out of San Francisco, is keen to see cities take up the idea of street lighting that doesn't just switch on and off to a timer, but responds to ambient light conditions and dims or brightens accordingly. It would follow the lunar cycle (weather permitting), and in so doing reduce the amount of electricity used in a big way.
Something like this could really help those of us with telescopes under the bed to pull them out again. So we can discover one of those comets hurtling toward the earth hell bent on our destruction.