Cornstarch And A Speaker
The above video demonstrates what happends when you place a cornstarch-water mixture, a dilatant, on top of a speaker. A dilatant is a material that responds differently to pressures; if you hit you apply a lot of pressure it will solidify but if you apply a little bit of pressure, it will act as a liquid. Now combine that with a source of varrying pressure, like a speaker, and you get some amazing effects.
What someone has to do now is to do the same expreiment on top of a speaker emitting a constant frequency in order to try to get resonnance patterns in cornstarch.