Valentine's Day. For many, it's the time for lovers to find each other the perfect manifestations of their affection. But for some, it's also the time to find out where their lover keeps sneaking off to at night.At NowAuto, a chain of car dealerships in Arizona, the technology to trace your valentine is now offered in the basic feature package. The NaviCom Mobile Location Unit is a GPS monitoring system that pinpoints the exact location of a vehicle and allows the subscriber to track its whereabouts on a digital map. While NaviCom does not promote the use of its technology for surreptitious means, Barry Mitchell, former manager of the NowAuto in Mesa, Ariz., acknowledges that the door is wide open for subscribers to use the system however they want.