There are a lot of videos on youtube that show resonance patterns in various materials. There's even a name for it: cymatics.
One of the coolest ones I've seen makes life-like forms emerge:
http://www.youtube.com/watch?v=4shodbQMcmM
There seem to be entire religions/philosophies built around sound frequencies and the resonance patterns that emerge from the boundary conditions.
But they're fun to watch.