This Bop Spotter project is absolutely brilliant:

I installed a box high up on a pole somewhere in the Mission of San Francisco. Inside is a crappy Android phone, set to Shazam constantly, 24 hours a day, 7 days a week. It's solar powered, and the mic is pointed down at the street below.

Heard of Shot Spotter? Microphones are installed across cities across the United States by police to detect gunshots, purported to not be very accurate. This is that, but for music.

This is culture surveillance. No one notices, no one consents. But it's not about catching criminals. It's about catching vibes. A constant feed of what’s popping off in real-time.

If I had the technical ability to do this myself, I absolutely would. The recordings on the site are fascinating little slices of time.