Ask Ron Rivest if he's ever been whisked away by the CIA in the middle of the night, and he laughs-but he doesn't say no. At Peppercoin, a two-year-old MIT spinoff in Waltham, MA, the renowned cryptographer oversees an operation far less secretive than an intelligence agency but almost as intense: a clearinghouse for electronic "micropayments," pocket-change transactions that may finally allow magazines, musicians, and a multitude of others to profit from selling their wares online. It's September, and with only weeks to go until commercial launch, Peppercoin's software engineers troubleshoot at all hours. Marketing executives shout across the room and over the phone, making deals.

But in the eye of the storm, Rivest is calm and collected. Eyes sparkling, real change jingling in his pocket, he even wears sandals with authority. What Peppercoin is trying to do, he says, is make it easy to "pay as you go" for inexpensive Web content-so you won't need to pay subscription fees, limit yourself to free content, or share files illegally. With a click of the mouse-and Peppercoin's software churning away behind the scenes-you can now download a single MP3 from an independent-music site, watch a news video clip, or buy the latest installment of a Web comic from your favorite artist. All for just pennies.

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