Marc-André Hamelin composed Circus Galop for the player piano. Performing it is impossible for a mere pair of human hands, but two people have tried to fake it until they make it. Another has transcribed it (or half of it, perhaps) for one player. Often, people will run it through a MIDI sequencer of their choice, to make a lively animation. Some have built Arduino robots that perform it. But, in the end, the best medium for a work this insane is the humble, yet manic player piano (less manic, but clearer-sounding performance here). Hamelin himself has run his composition through one, managing to get his television host to start dancing as the closing credits fade out...
Hobo Lobo of Hamelin is a thing by a dude, who’s all like, “I’m Gonna Make a Thing.” And then he did. Or is doing. Or, you know, whatever. This dude can be found on the internet. He websites to put food on his family. A wonderfully crafted and designed illustrated book for the digital age.
The story of the Pied Piper of Hamelin is best known to us from Robert Browning's versified account, here presented in an animated version and here depicted in stained glass. This article from the Fortean Times discusses possible factual bases for the story [hattip: BoingBoing] and this page collects similar accounts from other places.