Instructions:On 01 January Oyster launched a new series of 2 for 1 deals on things to do in London. They've added restaurants this time around, but also do musicals, west-end shows and more (including 2 for 1 at Blockbuster). Bargains to be had in London!
Visit the web site for more info, all you need is an Oyster card. Well worth having if you're visiting London because tube/bus fares just went up if paying cash, but are much lower with an Oyster. Oyster cards can be bought online or at any Tube station.