How about hooking up two computers with spotlights (or lasers?), then have them use the spotlight to send a messages that the other computer detects with the light sensor. You could set up a network, possibly over quite long distances. It might be a little slow and limited to line of sight, but how cool would this be!?!
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which would indeed be much faster, but misses out on the sheer geekiness of it.
How about hooking up two computers with spotlights (or lasers?), then have them use the spotlight to send a messages that the other computer detects with the light sensor. You could set up a network, possibly over quite long distances. It might be a little slow and limited to line of sight, but how cool would this be!?!