We posted Density a while back when we used mac address tracking (https://news.ycombinator.com/item?id=7305097). We've since moved to a wirelessly connected door counter, would love some feedback.
Glad to see the change in methodology! I loved the concept then and still do, but freaked out at the thought of my MAC address being logged everywhere I go.
We're happy with the change too. Simplified things. Any sensor trying to mass measure foot traffic across a city needs to be accurate, real time, anonymous, and cheap.
I had a similar idea, I wanted to place small microphones all over the city to know which places were "quieter" than others at certain times of the day etc... I was looking for a place and I wanted to live in a street that was quiet on weeknights