bcWebCam - Scan barcodes and QR Codes with your computer web cam
QuickMark - QuickMark makes everything possible.
ZXing - Barcode Scanner for Android
Barcode to PC: Wi-Fi scanner - Turn your smartphone into a real barcode scanner
Barcode & QR Code Scanner - A free app which allow to read and generate barcodes for Android.
MKH Barcode Reader - This tool can be used to scan QR codes on your PC or tablet. Note: a webcam is required.