I came across this interesting build by Philip Lens recently of a colour based synth called the Coltar.
It uses something called the Lego Mindstorms Colour Sensor. Lego has certainly got more sophisticated from when I was a kid.
Looking through Philip’s Youtube channel I found this really interesting generative music app for the iphone and ipad called the Colour Sound Machine.
It works on a gravity based system with dynamic blocks that can be placed anywhere on the screen. Different blocks have different properties such as tone, percussion, bounce etc… It’s a very interesting program similar to Reactable.