Stumbled onto this. Its the National Archives of Australia's search engine.
Great place to hunt down family members military history.
It has a massive data base and a lot of the files have been digitaly photographed so you can view the actual documents. To search for family members you will need a little bit of info - full name or service number, when and for whom they served, stuff like that. But I was able to find a few quickly. Do what i did and ring up your grandparents and ask them for info.
I also found some great yarns by just searching words like "casualties" and "court martial"
This stuff can be rather sobering, for a lot of the people's records didn't end well, often with plain words like "missing" or "Killed"
Anyway, if you have trouble using it PM me. It isn't the fastest search engine in the world but for the cold hard facts it finds, its worth it.