I just discovered this from a blog. There are some pretty cool ambient music creation apps on iOS devices that use a visual approach. One of these is called Bliss. Here is a short video. Pretty cool.
Of course, one can’t look at one YouTube video without discovering other music creation apps. Here are a couple of others, first Aura Flux:
And here’s the mobile version of Reactable, not quite so ambient, but fun:
Pretty cool, huh?