The Economist wrote that your desk lamp could become a powerful communications device:

• Lights can be made to turn on and off at a frequency that makes the flicking imperceptible to the human eye.
• This can thus be used to transmit information. It’s like Wi-Fi except instead of radio waves to encode 1s and 0s, waves of light are used instead.
• The main drawback of using it to replace Wi-Fi is also the technology’s main feature. Light can’t penetrate walls so you can’t ensure reliable internet across a home. But many businesses wish they could keep the internet within their walls for security reasons.
• Light might also be the best way to transmit information wirelessly on aircraft or in hospitals. While the effect is marginal, traditional wi-fi still has the tendency to interfere with the signals generated by sophisticated equipment.
• Since airplanes come with reading lights anyway, cabins could re-purpose them to save on the weight of cables and bring down fuel costs.
• Currently mainstream tablets and phones don’t have the technology to transfer information via light. But a simple USB dongle can enable the functionality. And it’s possible that smartphone cameras can be used for the task.
• The technology might even be embedded in street lamps to provide internet connectivity across a city.

The Economist has many more details about the technology.