Note: I've got a US audible account and a US Amazon account. I don't know if this offer will work if you have Australian accounts. Please let me know in the comments and I'll update as required.
(Update - confirmed working for Australian accounts as well as US. See comments)
Remember Amazon uses your billing address to work out which country you are in. So you can have a real Australian delivery address, real Australian credit card, Australian IP and a real US billing address (say the hotel you're currently staying in) and still buy US-only digital items. You can also swap back to a real Australian billing address whenever you want.
Deal 1:
Amazon.com have launched a new service called "Whispersync". If you own a book on both Kindle and Audible, you can swap between them without losing your place. ie Start reading the kindle version, then continue on in the car, where you left off, with the Audible version.
Here's a video explaining the new service.
Anyway to launch the service they are giving you 26 free kindle books (these are classics that have been free for a while) with the corresponding Audible audiobook (previously up to $30 each), also for free!
You'll need a Amazon account, and you can use that same account on Audible if you don't already have an audible membership.
Although if you haven't used Audible before, sign up using this link to get two free audiobook credits. If you cancel within the first month, you don't have to pay anything.
And with those two credits, you could use them to get 4 books with the following deal.
Deal 2:
Now, while I've got you attention - here's another Audible deal (membership required) that may interest:
Until 30th September, Audible have a Buy One, Get One free deal (BOGO) for classics on audiobook. There are over 110 titles from American, British, and European and World Literature.
(You'll need to be logged on and have available credits on your membership account to see, and take advantage of, this deal.)
Deal 3: (thanks to melmac77 and scupper)
Audible Win-Win Sale - until 18th Sept (members only)
200+ audiobooks on sale for US$4.95.
All work fine with my Australian accounts, tho I don't think my old Kindle Keyboard will be any use for the Audio Books