bcWebCam - Scan barcodes and QR Codes with your computer web cam
QR Droid - QR Droid Zapper
ZXing - Barcode Scanner for Android
QuickMark - QuickMark makes everything possible.
Barcode to PC: Wi-Fi scanner - Turn your smartphone into a real barcode scanner
Kinoni Barcode Reader - Use your iPhone as a professional barcode scanner for your PC or Mac.