I just found another option to get cash back on your grocery purchases - http://snap.groupon.com
- and these offers are good at any store!
Here's how it works:
First, you download the app for iPhone or Android or use the website to browse the available offers. Then you buy the promoted products at any store and snap a photo of your receipt. Upload your receipt within 2 days of making your purchase and you'll get cash credited to your account within 48 hours. When you reach $20 in earnings, you can request a payment. You can earn $1 for each friend you refer.
Snap is free to use, but if you don't redeem any offers for 12 consecutive months, Snap may begin charging a monthly Account Maintenance Fee which will decrease your cash balance over time.