Enjoying a concert by Jean Michel Jarre recently, I got musing over his many innovative and experimental ways of controlling the music. Including signature instruments like the laser harp, theremin, but also more conventional boxes, like the Minimoog and various Moog synthesisers, the ARP 2600, the Moog Liberation keytar synthesizer, Korg Mini Pops, and Roland HPD-15 Handsonic Percussion Controller, an iPad, and much more.
For even more experimental instruments, see the Elixir and Home Made Labor acts. They make they own instruments, sample it, tweak it, and create ambient sound-scapes. At a live performance a few years ago, they would mould and shape the sound as they went along, slowly adding complexity ad-hoc. Here's a video where they go into a bit of detail.