Here's a smart thing to do: Use your credit card rewards to save for your child's college education. You can earn 2 percent on your purchases with the Fidelity Investments Rewards American Express credit card and the Fidelity Investments 529 College Rewards American Express credit card. Upromise World MasterCard issued by Barclays Bank offers rewards of more than 10 percent when combining 5 percent Upromise MasterCard cash back with various Upromise online retailers. You can earn up to 8 percent when you use your Upromise MasterCard at participating restaurants. You can earn up to 3 percent back on gas, 2 percent cash back at movie theaters, and 1 percent back on all other purchases. Once you've accumulated at least $25 in rewards, they can be swept into a 529 college savings account where your money grows for education expenses tax-free. 'Every little bit helps' Granted, even at 5 percent rewards you'd have to buy an awful lot on your investment credit cards to make a dent in college tuition. Charges for in-state students at public four-year colleges, including tuition, fees, room and board averaged more than $17,000 for the most recent school year, according to the New York-based College Board. At private, nonprofit four-year schools, costs averaged more than $38,500. "You're certainly not going to be able to fund your kids college education this way," says Atlanta-based Beverly Harzog, credit card expert author and consumer advocate. Even if you charge $12,000 a year, at 2 percent that's only $240. "Enough to buy a book, maybe, two," Harzog says. Still, Harzog believes, every little bit helps. "It's not bad. It's just another tool you can use to fund your child's college education. And if it's money you're spending anyway, why not?" Even family and friends can help Personal finance columnist Liz Pulliam Weston likes investment credit cards because their rewards rate is typically quite generous. "Anytime you're above 1 percent, you're doing well," she says. They don't have annual fees and don't limit the rewards you can earn.