Chris Anderson talks about the Freemium concept.
Freemium is a business model that works by offering core services or products for free, while charging a premium for advanced or special features.
This business model has something for everybody: online enterprises, offline businesses, giant corporates and mom-and-pops shops.
Chris Andersons book, "Free: The Future of a Radical Price", will teach you how to integrate the Freemium model into your business and make your clients offers they just cant refuse.
You can learn more about the book here:
Chris Anderson (born 1961) is editor-in-chief of Wired, which has won a National Magazine Award for general excellence three times during his tenure. He wrote an article in the magazine entitled The Long Tail, which he expanded upon in the book The Long Tail: Why the Future of Business Is Selling Less of More (2006).