Thanks to Jon Husband for pointing out this example of the value of online social networks.

When radiation oncologist Michael Tomblyn recently saw a 21-year-old patient whose eye was protruding from its socket, he turned to his fellow physicians for help. Dozens of doctors offered suggestions, including fungal infection, HIV-associated lymphoma or a cocaine-associated sinus problem, eventually steering him toward the correct answer: rhabdomyosarcoma, a fast-growing cancer most often observed in young children.

The diagnosis didn't take place in a doctor's lounge. It happened on Sermo.com, a social-networking site for licensed physicians, which Dr. Tomblyn and 25,000 doctors like him visit regularly to consult with colleagues specializing in areas from dermatology to psychiatry.