To promote the new Nine Inch Nails album Year Zero, they had a whole alternate reality game set within the context of the album. It included shirts with secret messages, several websites with more hidden messages, and songs \”leaked\” on usb drives at concerts. It culminated in a free NIN performance in an abandoned warehouse for just 50 people that got \”raided\” by the police at the end. This forum has more info about the show and there\’s footage from it here. That\’s so damn cool.