The New Yorker had an article recently about a consultant who monitors blogs and messageboards for her client. She keeps her eyes peeled for keywords, "flame-ups", coded messages, and signs of attacks. It's something like the Tactical Messaging Department of Advomatic.

Only her client is the United States of America and she does her work for National Security:

Rita, who was born in Iraq and speaks fluent Arabic spends hours each day monitoring the password-protected online chat rooms in which Islamic terrorists discuss politics and trade tips. source

She describes her compulsive observations of these communities an addiction. The CIA calls it a breakthrough. "Occasionally, a chat-room member will announce that he is turning in his user name and password and going to Iraq to become a martyr, a shaheed."

Then Rita Katz takes action:

Katz then called an American counterterrorism official stationed in the young man’s country, and he, in turn, sent the jihadi’s e-mails to local investigators. Within twenty-four hours, they had him under surveillance, and a week later they arrested him.

An American intelligence official said, "In my opinion, they probably wouldn’t have had a clue if it hadn’t been for Rita.”

This, Katz said, is what she always hopes to achieve. She is an unsung hero who knows the first rule of communications: understand the medium.