We sent Morse code using a laser pointer a few years ago. Shoot the laser beam through a running 'muffin' fan. This chops the beam into a frequency that will be in the audio range. The beam then travels through the air, and hits a Radio Shack solar cell. The output of the solar cell was run into a small audio amplifier. You can then hear the audio tone, the frequency of which is determined by the speed of rotation of the fan. Using a simple shutter to open and close, blocking the beam, allowed sending Morse code to the user. The laser pointer was set up on a tripod and a spotting scope was used to align the beam onto the target solar cell. We achieved a half mile range, and were going to try going from one mountain top to another, but my helper got a job out of town, so we never went any further with it.
A Google search of laser chopper beam will show you lots of other ideas.

Jerry