Magnetic Resonance Piano by Andrew McPherson
This is absolutely brilliant but largely unexplored and lays open to a larger musical application. For one it calls out to classical composers, but could also be used brilliantly in experimental jazz, or in the studio. This is an acoustic instrument but has the ambiance of something beyond the usual acoustic experience. There are multiple methods for the use of magnetically induced vibrations, with many musical effects. There is both a version using a regular grand piano, with additional magnetic resonance features added, and a version where a more standard midi keyboard runs the magnetic resonance hardware on a standard piano.
More details:
http://instrumentslab.org/research/mrp.html
A very nice modern classical performance, i believe this was written by the inventor as well.