Here's an FAQ on what FlexiSpy is. Basically it is a program to install that sets the phone up to record sounds and log SMS texts and send them for you. This would probably be something really good for a parent to use.
That and an expensive data plan for cell phones as well. Those are expensive though, like 25-40 cents US per Megabyte :/ . Why pay that when my DSL gets like 0.0025 cents per gigabyte?
I know, DSL is so much cheaper. If parents really want to monitor anything, they just need to check the phon everyday! so hard to do....were too lasy now...