Consmr is another barcode scanner app that just released on the App Store that's targeted at groceries and pharmacy products. There are lots of barcode apps out there: ShopSavvy is one of the more popular, and we've covered RedLaser before, and all of these work pretty much the same: Aim your iPhone's camera at a barcode, and immediately get pricing, reviews, comparisons or even coupons all designed for whatever you've scanned.
If you've already found an app like this that you like, I don't know if Consmr has enough in it to pull you away. There are lots of other apps specifically for grocery shopping that offer plenty of solid features. But Consmr is free and easy to use, and it will deliver all of the information you need about whatever products you put under the scanner.
It can be very helpful, for example, to get some tips about competitive products while in the aisles at the grocery store, and Consmr will definitely do that. I worry a little bit about the objectivity of the app's listings (bigger brands such as Pepsi tend to show up easily while browsing, which makes me wonder, in perhaps a paranoid way, whether or not these listings are being manipulated for advertising purposes). But it's a free download and worth a look if you want a little more information or insight on what's going into your grocery cart.