Tomorrow begins the Exit Festival in Créteil (close to Paris) a great art exhibit where you can find artists' bricolage, hacks and tricks. One of my favorite piece of art is Veaceslav Druta's balancoire (i.e. the swing) which is a musical swing hanging from two wheels. The user/visitor sit on the swing. While swinging, he/she triggers the play of music that can change depending on the hands positions and the swing speed: There will also be Brad Hwang the guy who did the Incredible Strange Machines in 1993. Even though this one won't be at Exit, I cannot resist to put it here.

Using steam propulsion, Bratt Hwang constructed a huge instrument (10 meters long), consisting of 50 metal soup bowls which were suspended between floor and ceiling on metal wires. As the wires were vibrated by steam driven levers, the bowls functioned as sounding chambers. As part of the sound sculpture, the audience could eat soup from the bowls, thereby changing the quality of the sound.

Finally, Time's up (an austrian collective is also fancy) seems very appealing. Their SENSORY CIRCUS! looks good:

Sensory Circus is embodied in an interactive installation comprising an active, responsive and auto-generative audiovisual and architectonic system. The audience is central, and is principally responsible for their substantial contribution to the nature and dynamics of the whole environment

Through the different types of interaction with the components present inside Sensory Circus as well as their physical presence, every visitor mutates from a passive viewer to an active protagonist.

Sorry who the others I did not mention, there are also great!