With a reputed $2,500 annual fee and $5,000 initiation fee, the American Express Centurion card is the most expensive and most exclusive card in the world.

The Centurion card, which is also called the American Express "Black Card," is by invitation only.

"It's a status symbol," says Adam Jusko, founder of IndexCreditCards.com. "With the American Express Black Card, you're in the upper echelon with top athletes, rappers and celebrities."

American Express is decidedly hush-hush about the details of the card, which is available to only a teeny, tiny percentage of American Express customers.

When the card was launched in October 1999, Bankrate.com reported that American Express was offering Centurion membership to an exclusive 1 percent of American Express Platinum card customers. BlackCardSource.com estimates that there are just 17,000 exclusive Centurion cardholders worldwide.

Some of the card's reported benefits include access to a 24-hour personal concierge and travel agent, private shopping services at upscale retailers such as Tiffany's, complimentary companion airline tickets on international flights, and free stays and upgrades at luxury hotels and resorts.

Because of the ultra-exclusivity of the card membership and the fact that the card itself is made of titanium, Centurion cards pack a pretty serious wow factor.

"The Centurion card is a prestige thing," says Bill Hardekopf, chief executive officer of LowCards.com. "When they lay the card on the table people say, 'Whoa!'"