ZXing - Barcode Scanner for Android
ConnectUpz - Helping service businesses to connect and grow your customer base by becoming part of of a larger ecosystem.
MKH Barcode Reader - This tool can be used to scan QR codes on your PC or tablet. Note: a webcam is required.
QR Droid - QR Droid Zapper
QuickMark - QuickMark makes everything possible.
Obsqr - obsqr is an open-source, fast and lightweight QR scanner for Android.