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Software sold to parents to spy on their children, also helped marketers spy on them, without the parents or children knowing, documents from a U.S. District Court reveal.

EchoMetrix, a New York software company created and sold a program called Sentry Parental Controls, which parents loaded onto their child's computer to secretly view their web surfing history, chat conversations and password-protected instant messaging conversations.

Families were charged $3.99 a month for the service. When they signed up, they were required to provide the age and gender of their children.

The software company also sold a different program, directed at marketers and advertisers, called Pulse. It was billed helping marketers, advertisers and program developers learn what consumers were saying or thinking.

Do you think this software could be useful to you for spying on others?

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