A popular iPhone application that warns drivers of speed traps and red light cameras is now getting help from the Travis County Sheriff's Office. Since 2007, 4 million Trapster users have watched out for one another, especially from deputies like Tom Carpenter who wait on the side of the road with a laser gun in hand, clocking drivers who speed by. "If I can get my compliance with out writing a ticket-- I've done my job," said Carpenter.