We've probably all done it at one point or another — been so engrossed when talking on a cellphone that we've stepped out into a road without a second thought. To help you avoid causing chaos, a new app has been developed by university researchers from Dartmouth College and the University of Bologna, which employs the camera on the back of the phone to alert you to any oncoming cars. WalkSafe runs whenever you're on a call, and uses image recognition and machine learning algorithms to detect whenever a car is approaching you at 30mph or more, alerting you by vibrating the phone and sounding an alarm through the earpiece. It's a neat idea, though only having a camera on one side is an obvious limitation of the system — cross to the opposite lane and you won't receive any warnings. If you feel like giving it a try, the app's available for free in the Android Market.