Have a look at these wonderfully clever robotic art devices called Colour Chaser by Yuri Suzuki. They travel along the black lines that people draw and interpret any blots of colour they come across and convert them into sounds. Colours making music, how brilliant. Don't you just love a bit of synesthesia?
I found these via Plenty of Colour which is also worth a look.
Colour Chaser 2010 from Yuri Suzuki on Vimeo.