Ebook Central provides access to over 120,000 non fiction ebook titles on a wide range of subjects from a number of major publishers that you can read online or downloaded for a short period to your own device to read later.
The National Archives of Australia collects, preserves and provides access to Government records. Many records are available online for professional research or personal interest.
Open Library collects details of published books. It also holds loanable copies of ebooks including some about or from Australia. It makes audiobooks available to print for disabled people.
Project Gutenberg is an online library of free eBooks. It largely contains books that are in the public domain. These have been digitised by volunteers.