In this video, some scientists at Clemson University manage not only to levitate a water droplet using sound, but manipulate its shape—and the results are really cool.
By introducing the droplet into a pressure field created by a sound-producing transducer and a reflector that bounces the sound back, they get the now-flattened droplet to suspend itself in midair. Changing the sound issuing from the transducer causes the droplet to contort itself into varying shapes.
"Exciting" the droplet at different resonance frequencies causes it to form an oscillating star shape. The number of points on the star matches the harmonic being played. The third harmonic creates an oscillating triangular shape, the fourth an oscillating square shape, and so on.
When the pressure field strength is increased past a certain point, the droplet goes nuts, losing its symmetrical patterns and eventually disintegrating.
The research is from 2013, but the video has been making the rounds again now. Enjoy some fluid dynamics eye candy.