I agree with at least 50 of the suggestions above. Some of the best Australian albums would be:

Dave deHugard - Freedom on the Wallaby (essential)
Just about anything by the Larrikins - e.g., "The Larrikin Sessions" (essential)
Anything by Eric Bogle (e.g., "Songbook" - essential if you don't have any of his other albums)
Anything by the Bushwackers - particularly their early stuff before they got into folk/rock
Flying Emus - e.g., "This Town" - great Aussie bluegrass
Ted Simpson - one album of tall stories - "Piddling Pete and the Crosseyed Bull" - essential if you can find it!
Anything by the Backsliders - e.g., "Poverty Deluxe"
Anything by Tiddas - a great indigenous female group
Graeme Connors early albums

Other albums I like include most of Kristina Olsen's - e.g., "Duet" with cellist Peter Grayling - wonderful
Nancy Kerr & James Fagan "Steely Water"
Bandoggs
"Deep Lancashire"
Mary Chapin Carpenter "Stones in the Road" I am surprised nobody nominated Utah Phillips - just about anything!

There are so many choices, aren't there!!

Oh well.

ChrisP