Simple, Lightweight London Travel & Transport App - easily accessible Travel For London Tools:
London Tube Map 2014 (works offline)
Live Tube Status / Train Updates (tube.lu)
Live Bus Status / Bus Schedules (TFL)
Live Tube / Train Departure Times (TFL)
Plan A Journey/Route(TFL)
Call For A Taxi...
Simple Quick & Works — It's a simple app with essentially TFL services but it works and its easy to use. I personally prefer using this as its convenient for pulling up the tube map and checking buses arrival times.