Users of Transport for London's (TfL) Oyster card may soon be able to buy newspapers and milk and pay for car parking with their smartcard.
Plans could end worries about finding change for parking meters
TfL is looking at ways of making small payments a feature of the cards held by 2.2 million people in the UK.
Jay Walder, from TfL, said: "The dash to the cash point and worrying about small change for parking could be things of the past."
A similar scheme called the Octopus currently runs in Hong Kong.
TfL said stolen or lost cards can be stopped so no one else can use them.
A pilot programme has been running in the boroughs of Greenwich, Newham, Croydon and Lewisham where cards are being used in libraries and leisure services.