Ever since cell phones could play MIDI or better, I've had the opening instrumental section of Led Zeppelin's Kashmir [http://www.youtube.com/watch?v=tjtWrWeYARE] for a ringtone. I had it in MIDI on my old green-screen Sprint phone (y'know, from back when "PCS" was supposed to be a big deal), and my current phone plays an MP3 of it.