Social media has already proven it can help topple dictators, organize massive relief efforts and bring mass atrocities into the public consciousness.
It has also proven to be helpful for individual users by helping spread the word about their plight, and bring resources necessary to keep them alive.
This week a group of Georgia students began a massive social media campaign to help a fellow student stricken with a kidney ailment who is in need of a transplant. The student's friends hope their social media efforts will find him a donor kidney sooner than medical professionals, and there is precedence to believe it will.
Remember Amit Gupta? Gupta is an Internet entrepreneur who was suddenly diagnosed with acute Leukemia. He underwent and immediate chemotherapy treatment but was desperately in need of a bone marrow transplant he wanted to fully recover. Unfortunately (as far as finding donors is concerned) Gupta is from southeast Asia, an ethnicity which is severely under-represented in the donor pool, so his chances at finding a match were very, very slim. To increase Gupta's odds, his friends launched a massive social media campaign to increase awareness of both his specific plight and the plight of others in his same situation. The effort produced an overwhelming response; more bone marrow donors signing up than ever before and finally, a match for Gupta.
The fact is, whatever message you have, if it is worthwhile, people will not only respond, but also spread it around to their network. This then is what we describe as a viral message. In Gupta's case, as in the case of the Georgia student in need of a kidney, the message is urgent because the situation is dire, so don't expect your message about a sale on widgets to have a similar viral effect, unless it is tied to a similarly important cause (and even then it may seem to be pandering, which is bad.)
So, two lessons here: 1. Social media is a great place to launch your (potentially) viral message because it can motivate massive amounts of people to do great things. 2. Viral is only going to happen to the most important messages with a definite (positive) end in sight.