I am currently reading Cluetrain Manifesto (I know I am way late on this one).
In the essay “Markets are Conversations” by Doc Searls and David Weinberger, they talks about customers and word of mouth:
It’s nothing new, in one sense. The only advertising that was ever truly effective was word of mouth. , which is nothing more than conversation. Now word of mouth has gone global. The one-to-many scope that technology brought to mass production and then mass marketing, which producers have enjoyed for two hundred years, is now available to customers. And they’re eager to make up for lost time.
My Making the Switch blog gets about 1000 people stopping by every time I ask a question and I get 15-20 people leaving comments. The decisions to buy a Tom Bihn carrying case and Nokia 3650 were based on word of mouth and customers evangelizing.