When Jeff Bezos was launching Amazon.com a decade ago, conventional wisdom held that 300,000 titles would be plenty; the largest physical bookstores couldn't sell enough volumes to justify half that inventory. Bezos took what he calls "the bold, stupid path" and stocked his shelves with a million titles. Smart move: It turned out that early word of mouth came from people looking for more obscure volumes. These days, the site sells more than 20 million products, including all 29 colors of the KitchenAid 5-quart mixer. And it's a $6 billion business, thanks to its focus on niche markets and customer service. Wired caught up with Bezos at Manhattan's 92nd Street Y.