Roger, G3XBM once again turned me on to an interesting link, this one on a group of hams who are experimenting with communication over optical frequencies. This is a topic that has interested me greatly in the past (I seem to be interested in the extremes of amateur radio, both in terms of long wavelengths and short) and seems to be a rich area for experimentation. Check it out:

The Carolina Flashers Photonics Group – Welcome.

Addendum: They link to a fascinating demonstration of a German WW2 light-based transceiver system. Very cool.