It would be cool if the attendant was there and he/she had a paypal merchant account to accept a payment there on the spot where you can log into your phone and send a 20 dollar payment (or whatever the amount) and the attendant will start up the gas machine for you. Paypal could make it so fluid that everyone will be compelled to sign up for at least the mobile app, even if not everyone uses it all the time. Just like everyone really should have a sign on for Skype, even though they might not use it on a daily basis