Audio interaction. It’s one of the first things I show my students when teaching them about input beyond the keyboard and
mouth mouse because it’s so easy to do and so effective. You get an organic reaction to the sound level and attach it to whatever properties you want to affect on screen. It’s my Hello World for sound input libraries.
(It also makes me wish the bastards at O2 Germany hadn’t automatically extended my contract so I can’t get an iPhone, but that’s another story).
(Via Creative Review)