My very first arduino project:
I had 6 ultra-bright LEDs frozen in blocks of ice. The activity level of the lights was reflective of the activity level in the audio, which was a real-time feed from below the ice in Antarctica. This was from a research base in Antarctica that had placed two hydrophones below the ice shelf and broadcast online this kind of "antarctic white noise" with intermittent animal calls and splashes from animals diving in the water, plus digital artifacts from transmission, etc. I brought this feed into Pure Data to interpret the audio levels and then output light controls via PDuino interface to the Arduino.