terryking228:
I'm writing a library for these: http://goo.gl/FWMjI and I'd love to try some cool mapping ideas with your code...
I'm writing my own too. My test code is posted at http://arduino.cc/forum/index.php/topic,141363.0.html.
The big difference for my code is that an array of HC-SR04's all share the same trigger, then read pulse
time using pin-change interrupts (on mega).
It is kind of hard for me to generalize pin-change interrupts, so it is somewhat hard-coded.
more of an example than a good general-purpose library.