This app review should almost be an Android101 article.
Barcode Scanner is the de facto app for scanning QR codes (aka the square barcodes) that are frequently used in the android community to share links to apps. In fact, almost every android site out there that publishes app reviews will have a QR code somewhere on the web page that you can scan with your phone to download the app from the android market.
In fact, this review features one.
When I first got my phone, I kept seeing QR codes on android web sites and I had no idea what I needed to do to scan them... the answer is, you get this app and almost everyone knows that (but it doesn't seam to be written down anywhere).
If you have an android phone and you don't have this app, you're doing yourself a disservice.
Read more at www.androidcentral.com
Barcode Scanner is pretty straightforward. Open up the app, line up a barcode in between the rectangular viewfinder, and you're off to the races. If you're scanning traditional barcodes, Barcode Scanner will give you price comparisons on whatever product you're looking at as well as user reviews.