A new scheme will make small charity donations every time you travel in London using your contactless card.
Called Penny For London, it lets the traveller set the amount to donate, from 1p to 10p, for every journey. Every time you tap in using your card, that amount will be pooled into your account.
At the end of each month, that money will be donated towards helping London's poor and disadvantaged, as long as it's over 49p. If it's under, it will be rolled into next month.
You can set a monthly limit, so you can keep track of how much you're donating.
You'll have to pay for journeys using a Visa or Mastercard credit or debit card. The money will go towards the Mayor's Fund for London and other charities in the capital aimed at helping disadvantaged young people.
According to the organisers, if 100,000 people sign up, next year it would raise £1m. If 10 per cent of all Londoners joined, it could raise £15m.
"Penny For London is a big, bold idea that will revolutionise the way we give to charity," said Boris Johnson, Mayor of London. "The latest contactless technology is going to help transform the lives of thousands of young people across the capital.
"Enabling people travelling around the city to pool their pennies could potentially add up to hundreds of thousands of pounds."
Barclaycard helped develop the technology behind the scheme. "In a world first, we designed this new contactless payment system to make the process of giving to charity as quick and easy as possible," said Philip McHugh, chief executive officer of Barclaycard business solutions.
"We hope all of London will get behind the Penny For London scheme as these small donations will help make a big change to young people's lives."
You can sign up at PennyForLondon.com.