For some poeple, it may be as simple as looking up the time on a printed timetable at the bus stop or the notice boards at the train station. But if you've got a smartphone (iPhone or Android), then TripView offers a more convenient and, better laid out way of displaying current public transport info.
You can look up the stop or station at your current location (bus stop or station) and get an accurate time for the next bus or train, as well as info ones that just came past. It's easy to select routes and destinations, and not only does it show the time the transport will arrive, but also when you should expect to get to your destination. With Sydney's traffic, that's pretty much up to God though.
You can save your most frequent trips and refer to them in a few simple taps of screen, and you can even look up map routes so that you can be sure you're going the right way. For only $2.99, it's an indispensible app for a Sydneysider. I spent too long using the free version TripView Lite, which is great, but it doesn't allow trips to be saved. Glad i ponied over the cash for the full version.