Take a look at the photo at right. You may be thinking - "carrier pigeon". Not even close. Those pigeons don't have messages strapped to their backs, they have musical instruments. Yes, the dark objects appended to these poor birds' tails are Pigeon-Flutes (aka Pigeon-whistles, Pigeon Bells, or Tauben-Floeten).
These strange little instruments are essentially single-note flutes actuated by the wind passing over them as pigeons fly around. I'm nearly speechless... but not quite. I keep imagining what it would sound like to have an entire flock of musical pigeons flying around you. Here's an mp3 clip of a pigeon flute in action. According to the site linked up top, the high-end pigeon whistles are constructed to play a chord consisting of as many as 30 notes!
Madness would surely be the only possible result. Of course, if you're the type of person who spends your days strapping flutes onto the backs of pigeons, it just might be that no one would notice any difference when comparing your pre- and post-performance sanity levels.
Interested in constructing your own pigeon-based cthulian nightmare? Check out this ebay auction.