The Macquarie Atlas of Indigenous Australia, edited by Bill Arthur and Frances Morphy from ANU’s CAEPR, has just gone online. You can select a variety of overlays, including Indigenous social indicators, historical data, etc. Fun for the whole (map-loving) family.
Below is a map of the ACT, which taught me two things I didn’t know before:
- Each dot represents an estimated 50 people in 1788. So the best estimate of the Indigenous population of the ACT before European settlement was 50.
- The lines represent Tindale Map regions. I’d always thought that the ACT was fully encompassed by Ngunawal land, but actually a greater share of the area was traditionally the domain of Walgalu people.
Andrew Leigh's Archived Blog 2004-2010 
In case you are interested in cultural goings on, and not just numbers, ethnologue has a good map
http://www.ethnologue.com/show_map.asp?name=AU&seq=10
which is not to say you wouldn’t find Aboriginal culture without the languages.