I wish we could someday invent a device to absorb and convert sound energy into usable power. Such device can be placed in high level noise areas, for example busy subways or tunnels. Converted energy, in electricity form, could be used for lights or others at the place. Those lights can be easily programmed to turn on and off at a specific time interval. This is a similar idea of what we are doing now on those lights along some highways, the only difference is that those are powered by solar panels.