You can use the light system in your office as a complementary to your wi-fi system to transmit data, and even save a little bit in the lighting expenses. Those lights can also be colored to make a clear path to be followed.
Using a light sensing modem that is attached to the computers can be used to detect the LED bulbs installed in standard fixtures and thus transmit data. The back flow of the data can be done in a similar fashion.
Solar Keyboard
The Wireless Keyboard is a great invention, but have you got fed up with charging its battery, this is a solution for your problem and you can also save in the electricity bill. Now Logitech is coming out with a solar-powered keyboard. Don’t worry you don’t have to be outside your house to use it, the solar keyboards can charge itself with the lights you normally use in your house. They have enhanced a power-indicator light that tells you about the condition of the battery.