(FORTUNE Small Business) – All around him Thomas Cigarran sees dysfunction--and he couldn't be more pleased. No, Cigarran isn't vying to succeed Dr. Phil as the country's most lovable thuggish therapist. He's a seasoned company-builder who has come to believe that the greatest opportunities exist in industries that aren't working properly. No need to ask, then, why he's in health care. "There are just so many opportunities to make this sector more functional," says Cigarran, co-founder and CEO of American Healthways, which earned the top spot on our third annual FSB 100 ranking of the fastest-growing small, public companies. "To grow like this, you need to understand where the market is and how to reinvent yourself to capitalize on that."

Given the health-care system's chronic ailment--feverish costs being the most telltale symptom--Cigarran views his company's duty as one of coming up with increasingly effective prescriptions. At the start, in 1981, the Nashville-based business owned and managed hospitals. Consolidation eventually caused the company to divest itself of those hospitals and move into more defined niches such as a diabetes program for hospitals; in 1993, American Healthways spun off a separate company that opens specialized surgical centers. Now American Healthways is in the business of helping health insurers manage their patients--and hence their costs--more efficiently. (For more on health care, see "Hearts and Minds," page 74.)

In fact, the founders of most of this year's speedy growers seem to gravitate toward industries in flux . "Entrepreneurs look at a situation, and they think to themselves, 'I would have thought that someone would have figured out how to deal with this by now,'" notes David Birch, president and CEO of Arc Analytics, an economic research firm in Waltham, Mass. "That gives them the confidence to apply their own ingenuity."

Certainly the troika of trades that dominate this FSB 100--health care, banking, and energy--have experienced more upheaval of late than any combination of Dixie Chicks. Banking, which represents more than a third of the list, has ballooned as mortgage rates have deflated. That's created a higher rate of interest on the part of consumers, who are willing to take on bigger first mortgages and tap into home-equity loans. The shrewdest banks have adopted strategies that reflect their new popularity among consumers. Some have gone so far as to offer sludge-free coffee as well as semi-convenient hours. (For more on banking's new friendliness, see "For Love and Money," page 72). And while the bigger banks are too depressed--in stock price, that is--to entertain any more acquisitions, the smaller players are scrambling to collect as many branches as they can, the better to reach those eager consumers. Not long ago such doorfront outposts were scheduled to be replaced by Internet banking--but it turns out that conducting such mundane financial transactions as updating your portfolio requires a large-scale invasion by broadband, which has yet to occur. "Branches are back in vogue," declares Mark Zandi, co-founder and chief economist at Economy.com. "Some smaller banks have gotten very good at adopting retail skills."

Some of the turbo-powered companies ranked on the following pages have also developed skills in drilling down--literally and figuratively--into the active oil industry. This year's FSB 100 includes nine companies in the straight-forward business of exploration, yes, but also those that have positioned themselves as suppliers to the oil industry where--as you know, if you still drive an antiquated gas-powered vehicle--prices have risen steadily over the past few years. Demand has also welled up for natural gas, which powers many newer electric utility facilities. That said, those small energy companies may soon find themselves facing a crude reality, perhaps going the way of the telecom and software companies that formerly dominated our ranking (this year's grand tally of both sectors: two). Iraq didn't destroy its oil wells during the war, and the recent lifting of UN sanctions will enable it to sell its precious petroleum on the open market. As the price of oil drops-- assuming that other hot-spot sources of supply like Saudi Arabia and Venezuela aren't cut off--smaller drillers won't be able to make money in this underground economy. "The average energy price over the next three years is going to be lower than it was the last three years," predicts Zandi. "It takes time to get exports flowing, so it's not going to happen overnight." Two years from now, he says, "there will be no energy companies on a list like this."

He could be right. Or maybe he's underestimating the ingenuity of the leaders steering the FSB 100 companies, many of whom have found novel ways to register robust returns in the blandest of sectors. Restaurant chain Max & Erma's, for instance, has the audacity to sell something called The Garbage Burger (for more about that industry, see "Let Them Eat Nachos," page 64). Shuffle Master impressed the impresarios in Las Vegas by coming up with, of all things, a faster card-shuffling machine. (Is gambling becoming a growth industry? Read "Off to the Races," page 60.) One of just two software entries on this year's list, EPIQ Systems, had the clear-headedness to target a market few wanted to see take off, software used to expedite bankruptcy filings (for details, see "The Tech Holdout, page 58"), proving that the best opportunities aren't always where you'd like to find them.

However unglamorous some businesses on this list may look, they all had to meet the same qualifications. Aided by Zacks Investment Research, we started with a pool of U.S. companies, publicly traded on the major exchanges, that posted under $200 million in annual revenue. We ranked those companies not only by revenue growth but also by earnings growth and stock return (including dividends) over the past three calendar years. To come up with the final order, we averaged the rankings. This year's list shares only 23 companies with last year's--and just six from 2001, our inaugural FSB 100. (To meet a three-time winner, turn to page 68.) Cigarran, the 61-year-old CEO of our top company, doesn't expect American Healthways to remain a blazingly fast grower--unless it moves into new markets. "I'm a believer in niches," he says. "I like to be a giant in the land of the pygmies."

Five years from now, for example, he expects the company will grow by selling health services directly to consumers, who will find their benefits continuing to shrink. "People will pay for care," he says. "They'll pay out of their pockets for a nurse to call their elderly parents on a regular basis." They'll also pay extra, he thinks, to learn more about their own health issues. "Health care is a mess, and we'll just keep focusing on what's not working," he notes. Of course, other areas are ailing too: airlines, for example, and public education. And if he's so good at it, why not try to fix some of the problems in the country's political system? "No, no, no," he says, pausing to think for a few seconds. "There may just be some things that are too dysfunctional." Then again, they could be waiting for the right entrepreneur.