Well, lucky for me there exists a nice Helsinki public tranport app for N9/Harmattan, called Meegopas. As for banks, I use the normal browser interface, I've never even tried banking applications so I do not know if they are any good

I woud assume that the interface to get public transport information is open or at least available without authentication/encryption on any service that already has an app for android. It should be no problem to write an application for any platform using that interface.