In 1988, a British mountain climber named Joe Simpson wrote a book called Touching the Void, a harrowing account of near death in the Peruvian Andes. It got good reviews but, only a modest success, it was soon forgotten. Then, a decade later, a strange thing happened. Jon Krakauer wrote Into Thin Air, another book about a mountain-climbing tragedy, which became a publishing sensation. Suddenly Touching the Void started to sell again.

Random House rushed out a new edition to keep up with demand. Booksellers began to promote it next to their Into Thin Air displays, and sales rose further. A revised paperback edition, which came out in January, spent 14 weeks on the New York Times bestseller list. That same month, IFC Films released a docudrama of the story to critical acclaim. Now Touching the Void outsells Into Thin Air more than two to one.

What happened? In short, Amazon.com recommendations. The online bookseller's software noted patterns in buying behavior and suggested that readers who liked Into Thin Air would also like Touching the Void. People took the suggestion, agreed wholeheartedly, wrote rhapsodic reviews. More sales, more algorithm-fueled recommendations, and the positive feedback loop kicked in.

Particularly notable is that when Krakauer's book hit shelves, Simpson's was nearly out of print. A few years ago, readers of Krakauer would never even have learned about Simpson's book - and if they had, they wouldn't have been able to find it. Amazon changed that. It created the Touching the Void phenomenon by combining infinite shelf space with real-time information about buying trends and public opinion. The result: rising demand for an obscure book.

This is not just a virtue of online booksellers; it is an example of an entirely new economic model for the media and entertainment industries, one that is just beginning to show its power. Unlimited selection is revealing truths about what consumers want and how they want to get it in service after service, from DVDs at Netflix to music videos on Yahoo! Launch to songs in the iTunes Music Store and Rhapsody. People are going deep into the catalog, down the long, long list of available titles, far past what's available at Blockbuster Video, Tower Records, and Barnes & Noble. And the more they find, the more they like. As they wander further from the beaten path, they discover their taste is not as mainstream as they thought (or as they had been led to believe by marketing, a lack of alternatives, and a hit-driven culture).