The Eco-AdvantageIntroducing the Green 50, a collection of entrepreneurial companies that are showing what it means to run good businesses, attack the most pressing problems of our time--and make serious cash along the way. Every few years or so, American companies and consumers embrace the concept of green business. But something seems different about our current green awakening. This time, the action is being driven as much by markets as morality. Here's a look at 50 of the most intriguing companies that are helping to drive today's green revolution. From Inc.com