TfL and Recyclebank have officially launched an app that's been in trials for several months, where you can earn reward points for walking and cycling around town.
We've been playing with re:route and it seems fairly straightforward to use (especially once you've taken the introductory tour): create an account or sign in with Facebook (you can turn oversharing off), tell it where you want to go and it'll plot various methods for you to get there by public transport, cycling or walking. It even factors in cycle hire, telling you how many available bikes and docking stations there are at your start and destination racks. It calculates how many calories you've burned, how many kilos of carbon dioxide you've 'saved' and how far you've travelled. It even has badges to unlock à la Foursquare and there's a nice sense of community on seeing how many other people are cycling at that moment.
You get five points per completed journey (and 75 for signing up), which can be redeemed via the Recyclebank website. You can pick up money off or cheap deals for as little as 15 points and although some of the participating shops/restaurants etc are limitingly specific, chains like M&S, Cineworld and Origins are taking part. Not bad for taking a walk.