It's already happening in a few cities. Lone drivers who want to use car pool lanes can stop at informal gathering spots to pick up passengers who need rides. But passengers aren't always going to the same destinations as drivers-and some drivers prefer quiet passengers to talkative ones. So information science researchers Paul Resnick of the University of Michigan in Ann Arbor and Marc Smith at Microsoft are creating a computerized system that will make it easier for drivers and passengers in any city to find happy car pool matches. Called RideNow, the system starts with a Web interface where users can log in, specify their preferences, and enter their destinations and the approximate times at which they want to travel. Software matches up drivers and passengers, calls both parties' cell phones, and patches the calls together so that the users can negotiate a meeting place. Resnick says tests of the system should start this fall in Ann Arbor. Later, Resnick hopes, startups might want to commercialize the service in cities without extensive public transportation, perhaps charging a subscription fee.