If you're looking for a price/comparison shopping app, I've had pretty good luck with Sccope. Note it will only scan barcodes if your BlackBerry has an autofocus camera.
The Amazon.com app (amazon.com/bb), through the Amazon Remembers feature, will also let you either take a picture of a product or scan a barcode, although it can sometimes take a little while to return a product match.
I've actually had good luck with the AT&T one. I expected failure and got an ap that works pretty quickly and doesn't store the image like others I've used (though I don't remember which those were).
Posted from my CrackBerry at wapforums.crackberry.com