1. There is a "song" titled "The Ballad of Richard Nixon" by John Denver. The song itself is 4 seconds of complete silence (iTunes version), and yet, it is 99 cents on iTunes. On YouTube, it is 10 seconds. However, the length does not matter, since it is just silence.
(Warning: Do not turn your volume to max since the silence will be so powerful that it will blow away your eardrums.)