Barcode Scanner 4.6
The official Android app of the open source ZXing project:
http://code.google.com/p/zxing
Barcode Scanner uses the camera on your phone to read barcodes and look up product information such as prices and reviews.
It also reads 2D barcodes such as QR Codes and Data Matrix. These can contain links to web sites, contact information such as phone numbers and email addresses, and more.