Hi,
I was thinking about cutting an RJ-45 cable and hooking up the differential transmit wires to an LED (through a differential to single ended transformer) and then hooking the differential receiving wires up to a photodiode through another differential to single ended transformer and aiming them at eachother! :) Would something like this work? I am sure that amplification would be required also, and everything would have to be fast enough for 10mbit operation at least, but it seems like a quick way to make a wireless internet without any special software required as it would essentially just be a repeater..
cheers, Jamie