Imagine you're standing on a rooftop, looking down on the people in the street below. What if you could simply point out someone from the crowd and have them play the musical instrument of your choice? With enough people selected you could spontaneously create a little symphony. That's the concept behind the Sounds of Hamburg which gives you a view of life in the city through a collection of live webcams. Simply click on the traffic you see within each webcam and you can assign musical parts to people obliviously going about their day, then sit back and listen to the music generated. Once webcam will let you play with pedestrians, the other automotive traffic, while the third, and my favourite, uses the movements of fish inside the Hagenbeck tropical aquarium.