The consumer behavior most valuable to most marketers has less to do with what the buyer is doing than where they are at a given moment. For a decade, search services and ad targeting coveted simply knowing where someone lived. Now, mobile technology has the potential to let the marketer know which city or town block the person is on right now. That is, if the consumer lets the marketer in. Location-based services (LBS) has become the new third rail of privacy concerns. It is the kind of technology that reminds consumers how intimate digital tracking can become. But LBS is also the kind of technology that just as easily reminds users how much value bleeding-edge digital platforms can add to their lives.