A number of financial institutions now offer reward cards that promise to help you boost your net worth by contributing to your savings accounts, your retirement plans, your college funds or even your mortgage.

In fact, two recent entries into this field, Bank of America's "Keep the Change" debit card program and American Express One's "Savings Accelerator," are being marketed as an antidote to our nation's miserable personal savings rate (we just dropped below zero again).

Each of these cards, however, has traps for the unwary that could undo most or all of the benefits they promise. You should read the fine print of each offer, note how rewards are accrued and refrain from carrying balances; otherwise, any benefit you get from the savings-reward program will be more than wiped out by interest costs.

Furthermore, there's no card that is best for everyone. The right rewards program depends on how much you spend and other details of your financial life, like where you keep your retirement money. The Fidelity Investments reward cards, for example, are favorites of Curtis Arnold, who runs the CardRatings.com Web site. But their generous rebates won't be much help to you if you're not a Fidelity customer.

Even at their best, none can take the place of a disciplined savings and investing strategy. You still need to save on your own for retirement, college and

Some people lie about their debts, and some people are in denial.

But when a survey says 90% of Americans are either liars or in denial about how much they owe on credit cards, you can bet it's the surveyors who are the delusional ones.

In June, CreditCards.com released a GfK Roper poll that purported to detail Americans' relationships with credit cards. The survey contained plenty of interesting tidbits, but the poll takers went aground when they tried asking how the respondents' credit card debts compared to the national average. Here's a quote from the release:

"By some estimates, the average American household has over $9,300 in credit card debt. Yet, despite Americans' concern about their spending habits, few people are willing to own up to their balances: over 90 percent of survey respondents believe they had the same amount (as) or less debt (than) the average American. This makes a revealing statement about America's complex relationship with credit cards."

Actually, it makes a revealing statement about how pernicious a false statistic can be. Those of you who have read my previous columns about the myth of the