There was something posted not too long ago that bounced radio signals off of the moon that they then turned into an audio filter based on their testing on what it would do to the signal.
I like the example audio file they have for the article, because the QSO ends with "73, bye bye" and that bounces off the moon and is received by the sender a little bit later. The moon is far away!
(I also really enjoy the distortion to SSB signals that you get by tuning the "carrier" frequency slightly wrong; more likely in this case because the moon changes the frequency of the reflected signal due to the doppler effect. Also happens with satellite comms, though you might not notice if you're using FM and not SSB.)
