100 Brilliant Companies 2011Entrepreneur's annual look at the brightest ideas, the hottest industries and the most insightful innovators

"Good ideas are common," the aptly named British humorist Ashleigh Brilliant once said. "What's uncommon are people who'll work hard enough to bring them about."

Thank goodness, then, for the entrepreneurs on our annual list of 100 Brilliant Companies, who have coupled genius and execution to fantastic -- and, in many cases, fantastically lucrative -- ends. We picked 10 areas, some that have been booming for years (mobile tech, seniors) and some that are just now hitting their stride (social shopping, startup-to-startup), and spotlighted some of the most innovative and inspiring companies in each. The brilliance runs the gamut, from a deal site aggregator recognizing a void in a crowded sector to a service that simplifies the notoriously difficult process of creating an app.