Just noticed an app called AllSubway show up (59p/99c). It has the official london tube map, as well as Paris, Barcelona, and 8 more. It has NYC but that doesn't look like the official map. I very much they've got the rights for these images so grab it while you can, particularly londoners. I'd bet my lunch it won't stay up. Very cheap too! The maps are in the app rather than fetched over the air. You pinch/slide to navigate.