bcWebCam - Scan barcodes and QR Codes with your computer web cam
Barcode to PC: Wi-Fi scanner - Turn your smartphone into a real barcode scanner
ZXing - Barcode Scanner for Android
MKH Barcode Reader - This tool can be used to scan QR codes on your PC or tablet. Note: a webcam is required.
Barcode2Win - Transform Android device into a Windows WiFi barcode scanner
QR Droid - QR Droid Zapper