Cephalopods like squid and octopuses change their appearance with color-changing cells called chromatophores. Chromatophores can be stimulated via electrical signals — like the ones coming out of the headphone jack of an iPhone playing Cypress Hill's "Insane in the Brain."
This is almost too awesome for words. For those of you too anxious to wait, the needle drop is at 12:00. For the rest of you, here's some background: