I haven’t tried this out yet, but Frucall lets you comparison shop by calling them on your cell phone from a store and entering the bar code of what you’re thinking of buying. [via Physics Geek] Their system will check in their database of products, providers, and prices and let you know a range of prices, where you can get that item, etc. It’s a free service, from what I can see, except for whatever your cell phone provider charges for the call. If you are at your computer, you can also just search their database directly. I tried that much out with a couple of things I had lying around with bar codes on them, and it seemed pretty useful, when it actually had the product listed. It seems to tend towards electronics products, and not so much foodstuffs or random household goods.