Over-sharing on social networks has led to several arrests. A teenager who posted on his Facebook (News - Alert) page about shooting up a kindergarten class was sentenced to months in jail for making a "terroristic threat." A mom who posted a photo of her baby with a bong on Facebook was arrested in 2010. Instagram photos of guns and money led New York City law enforcement to its largest gun bust ever. Earlier this summer, a man used Facebook to confess to his wife's murder.

These incidents and countless numbers of others have led to the inevitable: social networking sites are being tracked. There is a growing customer base for Internet monitoring contractors. These contractors sift through your personal information that is readily available online. Besides feds, law enforcement and marketeers, some school systems have enlisted the aid of these contractors to monitor students on social media sites for cyberbullying. A suburban Los Angeles School paid Geo Listening, a social monitoring service, $40,500 to monitor 13,000 middle school and high school students. In all, eight schools were monitored. 

While monitoring the schools, Geo Listening discovered a student who was posting about taking his own life and was able to get him help. The goal of these monitoring companies is not to get kids into trouble, but to identify when intervention is necessary.

As tools improve, the easier it becomes to get a flood of data. With Twitter (News - Alert) heading toward its IPO, it will be making its exclusive 'firehose' of data available for a fee to a growing number of third parties. 

Firehose is valuable tool to marketeers. BrightPlanet, a data consulting firm, found a way to make it even more valuable and affordable to police departments. BrightPlanet's "Bluejay Law Enforcement Twitter Crime Scanner" allows law enforcement to do specific searches within Twitter's firehose for only $150 a month.

Social media monitoring services are being sold on the platform that they can prevent bad things from taking place, but does that justify it?

Jay Stanley, senior policy analyst at the American Civil Liberties Union, told NBC News, "We could stop bad things from happening if we install cameras in everyone’s bedroom in America. Which trade-off are we willing to accept? Every word, every fleeting thought we type into a search engine and every product we think about buying gets recorded by a large database, not to help us but to exert power over us."

If you use sites like Facebook and Twitter, "you should expect the world to read it," says Andy Sellars, a staff attorney at the Digital Media Law Project. "And you should expect that world to include law enforcement."