The app includes timetable information for all three of Sydney's public transport systems - train, bus and ferry - and will check to make sure the timetable is up to date each time you open the app.
You can navigate through the mine of Sydney's public transport in a few different ways. you can select the train stations, bus stations or ferry wharves you wish to start and end at, or you can select which suburbs you wish to travel between on Sydney buses. Once you've entered in your start point and end point, the app will give you timetable information as to when the next (and subsequent) train, bus or ferry is leaving.
You can set up as many different public transport routes as you like, and the app will also let you know of any trackwork or other delays likely to screw up your day. It's a $2.49 app, but a must have if you ever want to succeed in navigating the cesspit of Sydney's public transport system.
And while this is a very Sydney-centric app (because this is where Giz AU is based), we've also heard good things about Tram Tracker for Melbourne...