Oyster card

London Underground Oyster card. I got mine as even though I live in the midlands, Im going to Sydney from Heathrow later in the year. It will be so much simpler to swipe this card than having to faff around with change and paper tickets for the tube, especially when you have luggage.

The Oyster card is a contactless smartcard, with a claimed proximity range of about 8 cm (3 inches). Travellers touch the card on a distinctive yellow circular reader (a Cubic Tri-Reader) on the automated barriers at London Underground (also commonly known as the tube) stations to 'touch in' and 'touch out' at the start and end of a journey (contact is not necessary, but the range of the reader is only a couple of centimetres). Tram stops and buses also have readers, on the driver/conductor's ticket machine or, in the case of articulated buses, near the other entrance doors as well. Oyster cards can be used to store both period travelcards and bus passes (of one week or more), and a Pay as you go balance.

UPDATE: The Oyster card is so easy and convenient to use its fab. Plus I love the underground, you Londoners dont know how lucky you are!!