Viral marketing strategies

Viral marketing is a compounding function. A marketer does something and a consumer tells five or ten people.  If the cycle repeats itself, then they tell five or ten people.  It repeats and grows and grows like a wild fire spreading through dry brush. The marketer does not have to actually do anything else. (Though they can help by making it easier for the word to spread, but in the classic examples, the marketer is out of the loop.)Seth Godin