This looks pretty interesting (in the US): http://www.paynearme.com/
Print out a payment slip on a website, walk into a store and finalize payment in cash, website merchant gets immediately notified.
From their Terms of Service: "Please do not confuse our PayNearMe payment service with use of a credit card, debit card or pre-paid/loaded card. There is no extension of credit. And since there is no credit extended, there is no ability to challenge or cancel the transaction through a chargeback procedure."