Train
Rail travel isn't really as common for backpackers in Australia as it is in Europe. Trains run along the east coast from Cairns to Sydney and to most other major cities.

The most common train trip backpackers will make is the three-day trek across the Nullabor Plain from Adelaide to Perth. Many people enjoy the trip and liked stopping in places like Cook (population: 4) along the way. Flights from Adelaide to Perth are around the same price if you want to do the trip in 4 hours instead.