In the POS section of the mobile app it would also be cool if the "Catalog" list had the ability to scan a qr code to add a product to the payment.
I think Farmers Market type scenarios. We'd print QR stickers for our products, stick them on the product, then when someone buys stuff, we open the POS screen, scan the different QR codes, ba-da-bing-ba-da-boom, they are read to pay.
Barcodes would work too.