A few links that might help...
IRS Links
State Tax Links
Consulate General of the US in Australia
Common Forms
United States
US Citizens and "Green Card" holders remain taxable in the US on their worldwide income even when residing outside the United States. If you are living and working outside the US you may qualify for certain US tax exclusions. Read more... 
Australia
We work closely with a number of Australian accoutants to provide a tailored service to our clients. The accountant we recommend will depend on your needs; in particular complexity and cost.
Read more...