So what's not to like? Plenty. ("There's always an asterisk," McKinley notes wryly.) First of all, you're not getting that low rate unless your credit is strong. Otherwise, expect to get bumped up to a more punishing rate from the start. In most cases, the rate is tied to the prime, so it could rise if the Federal Reserve keeps putting upward pressure on interest rates. (Indeed, some of the interest rates quoted here may have already moved up by the time you read this). And even though you have to hand over up to three years of company financials, nearly every issuer still wants you to personally guarantee payment. If your company goes bust, or an employee runs amok, they'll come after you.

What about all those discounts on things like gasoline, office supplies, and hotels? They're potentially quite lucrative, so long as you would ordinarily buy those items from those particular vendors. But in some cases, McKinley says, the "discounts" may be applied to prices that have been jacked up first. The best deals usually come on cards with high annual fees or high interest rates -- American and Delta charge a punishing prime plus 9.99% -- so you'll come out behind if you plan on carrying a big balance. (If you do pay off your bills each month, consider trading up to charge cards like AmEx and Diner's Club. Not only is the list of benefits broader, but you also get more flexibility. Diner's Club, for instance, gives bonus points that can be used with a wide variety of airlines.)

And this "free" stuff isn't likely to stay that way for long. Don't be surprised if your own customers start pressuring you to let them pay with credit cards, which would cost you a 1% to 2% transaction fee. The cost may be worth it, says David Robertson, president of The Nilson Report, who says the cards are becoming a genuine management tool. For starters, they're displacing letters of credit in small-business transactions. The appeal is the instant gratification: You don't have to worry about collection costs or late payments. "That money is going to be in your account tonight before you even ship the merchandise," he says. Card users also get management help in the form of periodic statements that help break down expenditures by category. Nilson expects you'll soon be able to download them into accounting programs such as QuickBooks to help you analyze and control your spending. An unqualified blessing? Hardly. But plastic doesn't seem quite as flimsy anymore.

TABLE: Cards With Low Interest Rates
TABLE: Cards With High Rewards

By Rick Green in New York
Rick_Green@businessweek.com

To: FINANCE