Vera-Maria Glahn and Marcus Wendt, both students at the School of Arts and Design, Kassel did a nice project, which they self describe as an “interactive sound environment”:

“The Orbiter takes possession of all senses. It is a place for visitors to lay down and relax, watching the firmament above them. With a small gesture, just pointing upwards, the visitor can insert new stars into orbit with unique visual and musical characteristics. The player is enveloped by the instrument; the music filling the ears, the body and space.”

I like the concentric design, which is in this case implemented with Processing. And exceptionally very mentionable is also the exhibition version’s interior design, which can be seen here.
Unfortunately it can’t be figured out well of the documentation, if and how good the interaction really works.

Links: Project microsite on Marcus’ Blog, Video