Somewhere in my collection I have an AMD 29K-based tablet that was used in São Paulo's stock exchange trading floor. It had a huge IR LED array that, I assume, was used to transmit orders to receivers installed near the monitors. I managed to boot it from ROM, but it seemed the machine was waiting for the transmitter to send it its boot image.

Would have been an interesting project. Considering the size of the array, I'd be able to control all TVs from the building one block down.