![Social media comes to health care - CNNMoney](http://1.bp.blogspot.com/-htG7vy9vIAA/Tp0KrMUdoWI/AAAAAAAABAU/e7XkFtErqsU/s1600/grey.gif)
What makes a social network valuable? Facebook , with more than 1 billion active monthly users posting photos, sending messages, and updati...
What makes a social network valuable? Facebook , with more than 1 billion active monthly users posting photos, sending messages, and updati...