I use NetSpend (5%, can be fee-free) and Mango (6%, $3/mo fee). Both have prepaid cards and attached savings accounts. The Mango requires $500 in direct deposits a month to get the 6%, so I direct deposit $125 per week and then do a payment to my credit card from that for $500 every 4 weeks. I leave $5000 in the savings side of the accounts for maximum interest. There are certain limits to be aware of with these cards so if you go this route, read the terms first. For example, there may be a limit on the amount of each transfer, so if you need to pay off a credit card before the promotional rate expires, make sure you leave enough time to do that if you have to break it down over several transactions or months.
When making a credit card payment, initiate it through the credit card's site, and enter the ABA/Account Number for the prepaid card (which is not the number on the prepaid card; it will be on the paperwork you receive with the card) as if it's a regular checking account. The amount of the payment will need to be on the prepaid card.
I've found these to be an easy way to earn more interest and I wish they would allow the high interest rate on more than $5000 per account.
