(FORTUNE Magazine) - Consider the FORTUNE 1,000 as a very long ladder. The companies near the top are duly celebrated. But drop down a ways and you'll find new names jostling to be America's great corporations of the future. This is where, as one CEO recently put it, you can watch a company before the law of big numbers starts to slow things down. Change happens fast, upsets are still possible, and momentum hints at what's to come.

Four of the six companies portrayed here are on the FORTUNE 1,000 for the first time--JetBlue (Research), Las Vegas Sands (Research), Metal Management (Research), and LifePoint Hospitals (Research). All of them increased revenues by 30% to 85% last year--among the fastest growth on our list. And like every great company, each has a compelling story based on real people, and even some trivia that might surprise you.

In a visit to Nashville we find a young woman relying on breakthrough therapies to fight HIV. In southwestern Pennsylvania coal miners labor 600 feet underground, digging the largest seam east of the Mississippi. And did you know that about a third of the steel you buy--from washing machines to that new Chevy--is recycled?

JetBlue No. 896

The low-fare favorite has hit a patch of turbulence lately as ambitious growth--193 new jets are on order now--bumped up against a 52% jump in fuel prices last year. Analysts say that things should smooth out quickly as the $1.7 billion company adds more lucrative short-haul routes. And it helps that there's always JetBlue's famous service, provided by people like flight attendant Ronald Gamble, shown here at New York City's John F. Kennedy airport.

Consol Energy No. 513

Miners Dan Carpenter and Clyde Gardner work 600 feet below ground in southwestern Pennsylvania's Enlow Fork mine, sending their harvest of Consol's 4.5 billion tons of coal reserves along eight miles of conveyor belts. The $3.8 billion Consol, which has the second-largest commercial reserves in the U.S., is enjoying fresh demand this year. That should mean plenty of work for Gardner, a 30-year veteran of the industry.

Gilead Sciences No. 801

Marvelyn Brown's white-blood-cell count was so low that her HIV nearly progressed to AIDS. Then she started taking Gilead Science's Truvada, the anti-retroviral combo that is the $2 billion Foster City, Calif., company's fastest-growing drug--and according to a recent study, possibly the first treatment ever to effectively prevent the spread of HIV. Brown, 21, an HIV-education worker in Nashville, says, "The medicines out there now have prolonged my life."

Las Vegas Sands No. 877

There's almost $7 million in chips on dealer Vivian Deng's baccarat table (right) at the invitation-only Paiza Club, a high-roller section of Sands properties like the Venetian and Sands Macao. Sands, which had sales of $1.7 billion last year, has carved a high-end niche in Asian-themed clubs with their own chef and concierge services, where some comped guest suites are 8,000 square feet and bets can reach $150,000 per hand. Pictured here: Lawrence Tien, Venetian lead butler; Simon To, Paiza Club chef; and Han Tram, club coordinator.

LifePoint Hospitals No. 834

Nine-year-old Ethan Tharpe gets personalized care from doctors like Gerald Russell at Jackson Purchase Medical Center, the only hospital in rural Mayfield, Ky. (pop. 10,349). LifePoint, with revenues of $1.9 billion in 2005, nearly doubled in size last year when it bought 23 rural hospitals, from Danville, Va., to Los Alamos, N.M. Of Tharpe, who has been treated at the center for years for a chronic heart condition, hospital CEO Mary Jo Lewis says, "He has grown up with us here."

Metal Management No. 895

The Chicago-based recycler relies on 1,600 employees, like inbound-materials inspector Jose Leite, who works in the company's Newark, N.J., plant, to process more than five million tons of metal a year. The company reaped $1.7 billion in sales in 2005, handling everything from old washing machines to railway steel shipped from Russia.