"Most online shopping mirrors brick-and-mortar stores," says Susan Lyne. "They're not taking advantage of what's uniquely possible online, the heightened sense of entertainment and competition." As CEO of Gilt Groupe, Lyne has reimagined online retail, offering 36-hour flash sales on everything from designer handbags to golf clubs to travel deals. Completely swapping out inventory daily—or employing Kiva robots to fill orders from the ever-expanding warehouse—is no small feat, but Lyne's prowess at managing the technical dance has goosed Gilt's revenues sixfold last year and it's on track to hit $500 million in 2010. As copycat flash-sale sites spring up, all eyes are on Lyne—who formerly ran Martha Stewart Living Omnimedia, ABC Entertainment, and Premiere Magazine—to keep innovating forward. Next up? Serving hyper-customized sales based on user demographics.