Over the past decade, we have built a country-sized economy online where the default price is zero -- nothing, nada, zip. Digital goods -- from music and video to Wikipedia -- can be produced and distributed at virtually no marginal cost, and so, by the laws of economics, price has gone the same way, to $0.00. For the Google Generation, the Internet is the land of the free.

Which is not to say companies can't make money from nothing. Gratis can be a good business. How? Pretty simple: The minority of customers who pay subsidize the majority who do not. Sometimes that's two different sets of customers, as in the traditional media model: A few advertisers pay for content so lots of consumers can get it cheap or free. The concept isn't new, but now that same model is powering everything from photo sharing to online bingo.