They say that if you love something, set it free. Good advice, but you still might want to keep your eye on it.

So the other day, I slipped a GPS tracking device into my wife’s car before she headed to work. I put another tracker in my 2-year-old’s diaper bag and sent him off to the nanny for the day. I still had a few trackers left and my parents were in town, so I also threw one into their vehicle while they took my son to the park.

Of course, I had never suspected any wrongdoing and, later on, when I reviewed the trails left by these GPS devices, they turned up nothing untoward. My spying was meant only as an experiment, but I still felt like a heel.

As well I should have. It’s precisely because of mischief like mine that tracking devices get a bad reputation. These small gadgets work by connecting to GPS satellites and cellular networks to follow subjects and report back their locations to their masters.

Once I sent them out into the world, I could look up the trackers online, either on the Web or through a smartphone app. They could also be configured to send me alerts based on various criteria. If my wife’s car left her office parking lot during the day or my parents’ vehicle broke the speed limit, I might get a text alert.

If your mind reels at the universe of Maury Povichian possibilities contained within these gadgets, you’re not alone.

Yet after talking to representatives at several GPS tracking companies and trying their products, I learned that there are many less icky, entirely defensible uses for such devices. For example, some parents use trackers to make sure their children get to school and back safely each day. Others build them into their teenage drivers’ cars so they can be alerted if they drive recklessly.

There’s also the elder-care market: GPS trackers embedded into medical-alert devices can help locate and provide emergency help for parents with Alzheimer’s.

And don’t forget the dog: A tracker attached to its collar can let you know if it wanders out of your yard and help you find it if it doesn’t come back.

The more I heard about these devices’ applications, the less unseemly they began to feel; indeed, for many people, GPS tracking could soon become a regular part of life.

Amber Alert

Among the companies pushing for this future is Amber Alert GPS, a Utah-based firm that was founded in 2007 after Russell Thornton, a businessman, lost his 3-year-old son at an amusement park. After a frantic 45-minute search, Thornton found the boy hiding in a play structure, but he was traumatized by the incident, and it spurred him to build a device that would help other parents avoid that fate.

Amber Alert’s tracker is about the size of a child’s palm, and it looks a bit like an old-school pager. It can be slipped into a pocket or backpack, or placed in a carrying case attached to a child’s belt loop.

Carol Colombo, the chief executive of Amber Alert GPS, said most customers buy the device for children ages 2 to 10: old enough to be mobile but too young to carry a cellphone. Still, the Amber Alert can act as a quasi-phone; with a press of a button on the device, your children can send a text or initiate a voice call with you, and you can dial in to the tracker and listen to their surroundings.

I found the Amber Alert extremely simple to set up and use. The company’s website, which allows you to configure and monitor the tracker, is well-designed and intuitive, and its iPhone and Android apps also work quite well. Amber Alert offers more customizable alert settings than any other child-tracking system I tested: Among them, there’s an option to receive an alert each time your child comes within 500 feet of an address listed on a sex-offender database.