Get your free Maps of London. Transport for London are offering 19 free maps covering the whole of London. you can order all 19 if you like. They are intended to be used as cycling maps, but are useful even if you arent a cyclist :)
If you are a cyclist they do contain lots of useful info about cycling in London, such as available cycle routes and locations of Bicycle Shops.
My mate has ordered all 19 and stuck them all on the wall of his bedroom to form 1 single massive map of the whole of London, it looks quite cool :)
You can order the free maps here