Commonly available in Latin America
www.pagoefectivo.la
You select 'pay in cash' in the online checkout, walk to your neighborhood convenience mart, and they scan a QR code (or you give them a code if you don't have a smartphone) linked to your checkout session. It rings up the total, and you pay the clerk in cash. Once you hand over the cash and the clerk hits confirm in their POS system, the online store is notified instantly that you have paid, and your order moves directly into processing or shipping.
That's great for people that don't have any online-capable payment method, but I'd consider it a huge step backwards for those that do and are comfortable using it.