Coupons for Gas?

I just ran across this article on CNNMoney that mentions that you can often find coupons for gas stations. This is something I've never seen.  We typically buy our gas at CostCo and today it was more than 10cents less than the usually lowest price regular gas station in our area.  Plus we get 2% cash back with our CostCo card, making it even better.

There is a Kroger with a gas station almost right next door, and I've attempted to look into their gas discount program, but haven't actually tried it out. I've read mixed stories on whether or not the discount is even available in our state.  I noticed another gas station in the Nashville area that wasn't connected to a Kroger but would give you a 10cent /gallon discount if you scanned your Kroger card (but it had to be the big card and all I had was my keychain card).