Li-Fi? Maybe not a crazy as it sounds at first.

transmit data using waves of much higher frequencies, and without needing a spectrum license from your country’s telecoms regulator? Light, like radio, is an electromagnetic wave, but it has about 100,000 times the frequency of a Wi-Fi signal, and nobody needs a license to make a light bulb. All you need is a way to make its brightness flicker very rapidly and accurately so it can carry a signal. (via A plan to turn every lightbulb into an ultra-fast alternative to Wi-Fi – Quartz)