Interesting article about people with synesthesia.
“When Matthew Blakeslee shapes hamburger patties with his hands, he experiences a vivid bitter taste in his mouth. Esmerelda Jones (a pseudonym) sees blue when she listens to the note C sharp played on the piano; other notes evoke different hues–so much so that the piano keys are actually color-coded, making it easier for her to remember and play musical scales.”
Read more : Scientific American: Hearing Colors, Tasting Shapes