There probably aren't a lot of specific examples because there is soo much variety in what you might want to draw in response to your audio.  It's entirely up to you.  So, the question is:  what do YOU want to draw, and what aspects of it do YOU want to control with the audio?

For example, let's say you determine that FFT bin #10 (for example, number picked at random) is representative of a kick drum that occurs regularly.  So, what do you want to do about it?  How about every time that value exceeds some threshold you draw a red square.  Now you have a red square kick drum visualizer.  Get it?  Or any of a million other things, for ex...  Use an fft value directly to scale an object (so it gets "larger" when the fft of that frequency is "louder").  Or use the fft value as rotation, or to change color, or to accellerate it in some direction, etc...  Or use *changes* in fft values, between frames, rather than the values themselves, to control stuff.  (say, the delta of bin 10 controls an X coordinate, delta bin 20 controls a Y coordinate, delta bin 30 controls a Z coordinate -- now you're "driving around" in 3D)  Or find something that can be controlled by the peak values of the fft bins, etc.  Use your imagination, plenty of other possibilities...

$.02:  Minim is probably the most versatile library currently, and has perhaps the best fft implementation.  ESS still has some specific usefulness when rendering offline to help fill a functionality gap in Minim.  The Sonia plugin still remains useful in live situations as you might (potentially) get some hardware performance advantage that the pure-Java libs (potentially) miss out on.  Others will likely have differing opinions.  ;)

hth