M Indicator is one of the best app I have ever come across. It basically shows you the mumbai local train timings including the western, central and the harbour line. Then it shows the Bus number, if u have the bus no. then its will show you the stops on which the bus will have its halt, if you have the bus stop number then it will show you the buses that comes to that stop.
Including this it has many more features like you can seen the Autorickshaw fare, Taxi fare, you can even check your PNR status if u have booked any long journey ticket. It has one more great feature the movie icon by which you can find which movies are going on and in which theater or multiplex.
This feature is freely available on android market for android user and on internet for normal user and on blackberry store for blackberry users basically anyone can easily find one for themselves.