just off the top of my head, i knew about the aphex twin song, i knwo there are a few songs, and one song that is accully done backwards, and you can play it forwards, and its a differnt song, but dosnt sound like its being played either way, aphex twin is a creative person, oter than that i know Incubus, Azwethinkweiz has a hidden message at the end, there are about a dozen more that i know of jsut cant think of them off the top of my head.