Go to http://ingdirect.com/ and open a cyber-savings account. It's paying 4.5% and your money is insured by the F.D.I.C.
The way to "work" the system is to put your money in there, and leave it in there, until the second day of every month. Interest is paid on the first day of every month. Then, on the second day of every month, after you've collected interest in your account, transfer out whatever money you need to pay credit card bills in to your personal checking account at home. Funds take three days to transfer, but credit card bills don't need to be paid until the 10th of every month. If you take your credit card payment directly into your bank at home (that issued the card), and pay off your credit card balance, you won't get nicked by late payments due to slow mail. (Some of those credit card companies take 10 days to get your account paid off).