Link: The Network Effect

Begin with an article on [steganography](http://arstechnica.com/business/news/2012/05/steganography-how-al-qaeda-hid-secret-documents-in-a-porn-video.ars). Follow link in comments to famous case of a [musician embedding an image in the spectrogram](http://www.youtube.com/watch?v=u-KMFxzA_Lk&t=5m30s) of a work. Discover that there are programs which will [do this](http://www.uisoftware.com/MetaSynth/index.php).