QR Droid - QR Droid Zapper
Camelcamelcamel - Easily monitor Amazon product prices and get alerts when they drop.
ZXing - Barcode Scanner for Android
Fetchee - Fetchee is a free price tracking wish list app that works with all online stores worldwide.
UpCode - UpCode is a highly developed mobile access & interaction MAI technology that turns mobile...
Keepa - Price history charts and the option to be alerted on price drops for all Amazon sites.