TOM: A few weeks ago, we answered a question from Blair, the mother of a 16-year-old girl, who wanted to find a device that would help her keep track of her "spirited" daughter's driving.

RAY: We suggested a convent.

TOM: We actually suggested one of the Global Positioning System (GPS)-based black boxes that can track a driver's speed and aggressiveness, and report violations to a parent instantly by e-mail or text message.

RAY: These devices are called Event Data Recorders (EDRs), and there are a number of them on the market.

TOM: But driving fast isn't the only danger to new drivers. Cell phones provide a whole new smorgasbord of ways to crash a car. There's the distraction of conversations, and even worse, the sending and reading of text messages, which multiplies the risk of an accident many times over.

RAY: Well, now there are cell-phone applications that you can install on your kid's (or parent's, or spouse's) phone to cut down on these distractions.

TOM: They all work pretty much the same way. They use the phone's GPS to determine when the phone is moving faster than walking speed. Then, it presumes, you're driving.

RAY: Of course, if you're riding the school bus, you're out of luck. But nothing's perfect, right?

TOM: Once the application senses that you're moving at vehicle speed, it shuts down some or all aspects of the phone. One app might turn the whole phone into a brick. Another app blocks texting. One is highly customizable.

RAY: In all cases, once the car is stopped for a certain amount of time, the phone is released again to fully function for the user.

TOM: A few of these apps have override systems so that, presumably, a passenger can program in some numbers and then text and chat while the driver pays full attention to the road. Of course, teenagers will figure out how to scam that one in no time.

RAY: They all allow you to dial 911 anytime, and allow certain "emergency numbers," like parents' numbers, to get through under all conditions.

TOM: They're not perfect, but they're worth a look. Their names are iZup, CellSafety, ZoomSafer and TXTBlocker.