(MONEY Magazine) – James Murdock, founder of Endless Pools, is a classic entrepreneur, a guy who makes things no one else would think of. In his case: pools and devices that create currents for lap swimmers. Like any good start-up maverick, he financed the business partly on his credit cards. And like any restless inventor, he's never totally happy. "The product really wasn't that good at first," says the 48-year-old. "And if I sold a pool to someone in Dallas, I'd have to drive to Dallas to make the delivery and install it myself." But Murdock improved his inventions, coming up with models that could be shipped. Result: Last year Endless Pools had revenue of $25 million. --J.F.