Safeway through just4u has a deal on Dominos gift cards. Save $7 on a $50+ card, and also get 10x fuel reward points. I just tried it and the deal stacks.
It's pretty decent. $43 for a $50 card, + 50 cents off per gallon on gas up to 25 gallons (up to a $12.5 value).
I have 2 spare 5 gallon gas tanks so I used those to reach 23 gallons on a fill up today.
Then many of us slickdealers will have 3-6% off grocery store credit cards. Next month is also 5% off on gas, so fill up with gas in the new year at 50 cents off a gallon + 5% off.
So if you are able to fill up with around 25 gallons and have a CC that gives CB at grocery stores you are looking at around $30 for a $50 GC (when subtracting the fuel rewards savings).