Lonnie Johnson

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But he's banking on something bigger than squirt guns and hair dryers. He hopes to revolutionize the $50 billion battery market. At a venture capitalists' conference in October, the usually shy and reserved Johnson charmed the audience, trying to drum up $10 million to produce an "energy storage device," which in layman terms is a rechargeable battery smaller than a penny that could eventually be used in cellular phones, laptops and pacemakers.

Seldom does Johnson have time to tinker anymore. He is so busy that he has a personal assistant to keep track of his meetings and travel arrangements. His new house doesn't have a lab in the basement, and he sometimes misses the old days. He still hasn't given up on the potential of the thermal heat pump that led to the Super Soaker discovery. He is also convinced that he has developed an idea for an ambient-heat engine--a motor powered by environmental heat and thermal energy. "As an inventor, it's a rite of passage to have an engine," he says. "I'd like to have my own engine someday."