NetJets

The market leader, with 48 percent of the pie, NetJets pioneered fractional jet ownership 20 years ago. Today it has at its disposal a wide-ranging state-of-the-art fleet of 624 -- which Berkshire Hathaway's Warren Buffett, who owns the company, once called an ''armada of planes positioned throughout the country'' -- making it one of the world's largest airlines. Prospective flyers can buy a 1/16th share of whatever jet suits their needs best -- from a Hawker 400XP for $406,250 to a Gulfstream 550 for $2.6 million. That gets you a spotless jet outfitted with your favorite drinks and reading materials, with anywhere from 50 to 400 hours of annual flying time. But as with all fractional jets, you not only fly the fleet (at about $1,554 per hour) but you also pay for the monthly upkeep ($6,820), which can add up quickly. www.NetJets.com