For anyone currently using the $500 gift card method like I am, this may be an easier alternative. It's the same cash back, but it's only one card so it's easier to keep track of.
Here is the card. All you have to do is buy $500 reload packs and load it onto the prepaid Amex. You can buy $500 MoneyPaks or $500 Vanilla Reload packs.
They sell the reload packs at many retailers that get 5% cash back. Ones that caught my eye were:
Office Depot (Chase Ink)
Gas Stations (Any gas card)
Drug Stores (Dividend, Freedom, etc)
Radio Shack (Cash+)
Im not sure if inside sales at gas stations get the 5% back. Any confirmation on this would help out, but the other ones I'm pretty positive would work, just like $500 gift cards currently do.
Just thought I'd put this idea out there. Seems like this would be easier than managing 2-6 new gift cards every month.