By KELLI B. GRANT | SmartMoney

As credit-card issuers slash bonus miles, flier miles and other perks, "charging it" has become a much less rewarding experience. However, there are still ways to make that plastic pay.

Fidelity and Schwab (schw) both rolled out credit cards in December that offer 2% cash back on purchases that get deposited directly into either a brokerage or IRA account. (See details below.) Even better, there's no cap on annual rewards, so big spenders can reap substantial benefits. (And there may be more of these card offers on the horizon: Fidelity plans to revamp its Investment Rewards and 529 College Rewards American Express (axp) cards this spring, offering 2% cash back into a brokerage or 529 savings plan.)

"That's a big carrot they're dangling," says Curtis Arnold founder of CardRatings.com, a credit card comparison site. "It's unusual to see two cards with such aggressive rebates." Typically, cash-back cards offer 1% on most purchases, with up to an additional 5% when you spend money in certain categories like at restaurants or gas stations. Overall, however, even the most reward-savvy cardholder usually earns just 1.5%, he says.

Before you rush to fill out an application, bear in mind that the new offerings are really a bid for deposits. Should the marketing push be too successful in attracting new cardholders, the banks could decide to scale back their rewards, says Arnold. And be sure the investment options (and associated fees) offered by these cards make sense for you.

Also, make sure you can pay your monthly balance in full each month. Both the Schwab and Fidelity cards carry high interest rates of 14.99% and 16.99%, respectively. "You'd be shooting yourself in the foot if you carry a balance," warns Linda Sherry, a spokeswoman for Consumer Action, a nonprofit consumer advocacy group.

If you're looking to put credit card to good use, check out these two new offerings, as well as a standby from Wells Fargo (wfc) that debuted in 2007: