By Mary Plummer
Most cab riders don’t know it, but everywhere they go is being tracked. The city’s been collecting GPS data from cabs, and recently a group at Sense Networks, Inc. put the data to use. Their creation: CabSense, an iPhone application that helps people locate the best corners to hail a cab. Sense Networks crunched the data from 90 million cab rides and came up with a map that plots the most popular historical pickup and drop-off points. The free application also features phone numbers for car services if you’re in an area like Brooklyn, where a yellow cab can be hard to find.