I myself will be visiting Australia next February and have started to research their coasters. And boy, do I have a new appreciate what we have over here! Talk about a coaster starved continent! I'm amazed that the biggest park only has 4 small coasters! But the parks themselves look pretty interesting and fun.
Go to the below link, then scroll all the way down to "Worldwide-Official Sites". Under Australia is the only 4 parks I could find info on. Dreamworld seems to be the best, with the Tower of Terror and Giant Drop, a 39 story freefall. Looks totally awesome!
http://users.sgi.net/~rollocst/a_state.html Post a TR when you get back!