If you're a parent looking for a low cost (but highly effective) way to keep track of your kids, then you should consider an iPhone tracking app.
As you probably are aware, the iPhone is the hottest cell phone on the market today. The latest iPhone 4 sold millions in the first week, further cementing its place as the most sought after cell phone. Since the iPhone is a very popular device, it's obviously the desire of most kids today. This means parents can use this as a tool to monitor and track their kids by installing an iPhone tracking application that will report the location of their children at any time.
The way tracking apps work, is soon after installation, they begin to report GPS coordinates at certain intervals (which usually you can adjust) or they will enable you to "request" the location of the iPhone user. Results are usually sent to an account that you set up at time of purchase. This enables you to then log in using any internet connected device and view the tracking data.
The cool thing is that these tracking apps will show display the GPS location on a map (usually Google Maps), which means you can zoom in, zoom out, get driving direction, and even use Google's Street View option to get a 360 degree view of the area. There is truly no better tracking option out there.
An iPhone-tracking application means no more worrying if your kids are in school or when they don't pick up their phone when you try to call them. With this type of app, you'll always have a way to find out "exactly" where they are at any given time.
One thing to point out is that not all of these apps are created equal. Tracking applications will fall into two categories. The first one being 'visible' and the second one being 'hidden' to the user. What this means that before you purchase an iPhone-tracking app to track your kids, decide if you want them to know you are tracking them, or if you'd rather not tell them. In most cases, the visible tracking apps are sold within the App store, whereas the 'hidden' iPhone tracking apps are sold outside the App store.
The best way to decide if you should purchase a visible or hidden app is to ask yourself how your children will react if you tell them that you have installed an app on their phone to track them in case of an emergency. My guess is that if you make it a condition of having the iPhone, most kids won't care. However, if you feel your older children will not like the though of mom and dad knowing where they go, then definitely go with the hidden tracking applications.
Regardless of your decision, using an iPhone tracking app is the best way to keep track of your kids, and that means more "peace of mind" for you and your spouse.