Android: Google's already got Goggles for visual search, and Google Shopper's mobile site can run bar-code scans. Google Shopper, then, is a free app that combines some of those features together in one package for those who love to find a deal.
Unlike Goggles, which aims to provide a greater search by image functionality, Shopper only wants you to take pictures of "cover art"—books, CDs, DVDs, and other items with consistent images and iconography. It can also perform bar-code scans when it doesn't quite get the picture, and if neither of those are working, you can simply type in the name of the product, or just say it for Google's hard-working voice-to-text translator.
In a test on a few objects this morning, Shopper was pretty impressive when it came to books and CDs. It was fast and efficient, too, over a (T-Mobile) 3G connection, bringing back results almost instantly. In the example pictured up top, the result was slightly askew—an audiobook CD instead of a paper book—but the results included the right product. Those results arrive in the form of a simple item-store-price list, though, and could be a bit more helpful. For our money, ShopSavvy offers a greater convenience, when it works, because it provides local prices, gives directions to get to the store with the better price, and has a more robust history and wishlist functionality.