Cover and Square are phone apps which allow to pay (in restaurants, stores, etc) using only your phone. No cash or credit card required — although you do need to have the money somewhere! If you have a geo-aware phone (and you have that feature enabled), you won't even need to touch your phone. Read all about it.
Do you already use a pay-by-phone app? If not, would you use one?
Do you already use a pay-by-phone app? If not, would you use one?