As Jordan Viator roams the conference rooms, dimly lit bars and restaurants here at the South by Southwest Interactive conference, she often pulls out her cell phone and uses the Foursquare service to broadcast her location The New York Times reports. Such a service might sound creepy to the privacy-minded. But it came in handy for Ms. Viator when she arrived Friday at a party in a bar called Speakeasy and could not find anyone she knew. Her friends who also use Foursquare could see where she was, and some joined her a few minutes later. “I only share my location with people I am comfortable meeting up with, and when I want to be found,” said Ms. Viator, a 26-year-old communications manager at a nonprofit company. Mobile services like Loopt and Google’s Latitude have promoted the notion of constantly beaming your location to a map that is visible to a network of friends — an idea that is not for everybody. But now there is a different approach, one that is being popularized by Foursquare.