Today only, Groupon offers Chicago residents a $40 Google Express Credit for $15 for new customers only. (Check availability for your ZIP code here.) Coupon code "JUMBO3" drops it to $12. That's tied with our expired mention from two days ago, a $28 savings, and the best deal we've seen for a $40 Google Express credit. Google Express is a delivery service that allows you to order from local grocers and retailers like Walgreens and Costco.