Peter Kirn, from the Create Digital Music Blog wrote an article about the Stockholm Music Hack Day, and the Echonest Midi Player is marked as one the coolest individual project among the 31 hacks presented!Echonest Midi Player
A Web-to-MIDI converter
Internet comes in, music goes out. Connect an Ethernet cable to one side of this gadget (via the Arduino Ethernet Shield), connect the other to a MIDI instrument, and Bertrand Gondouin’s creation plays MIDI music automatically.
Of course, this has other creative implications, like the ability to pipe your own music or musical events to installations, remote players, to rig up an Ethernet- (or wifi-) powered MIDI band, or whatever you might imagine.