Back when I was unemployed, I would spend a whole day driving from store to store for in search of deals, and I was frequently one of those irritating people buying the entire end-aisle of some canned good because it was such a screaming deal that I couldn't resist.
Now, I'm too busy to be an Extreme Couponer, but I do dearly love a good sale. Grocery Pal is a relatively new app for iPhone and Android, but it's a lifesaver for my hectic life, as it gives a run-down of ALL the local sales. It sees your location and can even be store-specific, it alerts you when items on your list go on sale, it has a manufacturer and store coupon database and it's intuitive and easy-to-use.
If you've ever wanted to be better at shopping sales or using coupons, I think Grocery Pal is the perfect solution. Just don't mind me if I'm staring at my phone is the produce section - I'm not texting, I'm looking for deals.