It has happened over the last five years, before our eyes. It is one of the marvels of our age (and the great unwritten case study of a business built on recommendation). It is Google. As a Media Guardian leader argues:
It grew by word of mouth with virtually no advertising and has seen off rivals to become the dominant engine, with 200 million searches a day and over 3 billion web pages indexed. Google is not only one of the wonders of the web, but has also become both a noun and a verb.
Google proves the the power of news and events (the stuff of most PR campaigns) to affect behaviour. Its Zeitgeist analysis of searches shows that by the start of September, public interest in the Notting Hill Carnival and the Reading Festival was declining (both events were by then history). Conversely, interest in the US Open tennis was surging.