Is there a lot of action in your neighborhood at 3 a.m.? Sense Network's Citysense allows users to look at cellphone usage patterns to gauge the flow of foot traffic in a city. The service will be available first in San Francisco and New York.

What's more, by studying urban movements, Sense can sort users into behavioral "tribes" — people who follow similar patterns, from neighborhoods to night clubs. So if the dots congregating down the street are red or blue, it might be lively — but not for your tribe.