Hi James.
There are a variety of useful publications. Two that we have used are:

For WA there are 2 volumes of a publication called "Priceless Campsites". It is excellent, but only covers WA.

The best known one is "Camps 4 Australia Wide" www.campsaustraliawide.com. Camps are displayed on Hema maps. Very easy to use, but lots of travellers use it, so many sites are often busy. It lists over 3,000 sites.

If you are a member of the CMCA, they will soon have an electronic, searchable Oz wide data base, available to members.

Chees,
Peter.