You're probably thinking of Delicious Library (https://arstechnica.com/gadgets/2004/11/delicious-library/) - that was such a cool piece of Mac software. I think it worked with the CueCat, but you could also use your Mac's iSight camera as a barcode reader. Even had the satisfying "beep" when you scanned a barcode. Scanning a QR code with a smartphone camera is super commonplace now, but back in 2004 it felt so futuristic.