People resent Big Brother for his creepy spying and infringement on civil liberties -- but what if he told you where all the awesome parties were? You'd like him; you'd call him Citysense.
Alpha-testing in SF only, CS is a Blackberry app that provides a real-time graphic representation of where-the-action-is, an offshoot of human-activity tech used to counsel business (e.g., telling Starbucks, "Why not both corners?").
How it works: CS pulls anonymous data from all manner of watchdog-ware (GPS, wifi positioning, taxi company data, etc), then plots the aggregate onto a grid, with glowing red spots signifying dense groups of people, each linkable to Yelp/Google for more info ("did you mean: clitoris park?").
For historical perspective, CS generates a plus/minus % of any spot's daily activity vs its 3-years average; meanwhile, green spots connote "unexpected" action -- a spike in population density that could indicate an event like a riotous concert, or a riot
Right now, CS tracks "where is everyone right now?" but once their system informs itself on user habits, they'll be able to answer, "where is everyone like me right now?" Safeguard your civil liberties when you spy a glowing red San Quentin.