Through September 30th, save .10¢ on every gallon of gas when you pay with a reloadable Walmart gift card, reloadable Walmart MoneyCard® or Walmart credit card. It would be pretty easy to grab a Walmart gift card and load it up with funds before pumping your gas to save some moola.
*If you're buying a gift card right before fueling up, make sure to ask about a waiting period, as some gift cards take 15 minutes or so to 'show' the money on it.
Check this out for more details and a list of participating states.
(thanks Family Friendly Frugality!)