Both the Ballarat and Broken Hill monuments are on the net, but don't ask the URL. A Google image search should find them. There used to be a memorial plaque on the bandstand in Kadina, SA, but some careless coot lost it. The Ballarat one is rather cute, with a profile of Titanic on its windvane.
Thanks to Andrew Rogers, there is now a monument on the grave of stewardess Evelyn Marsden in Waverley Cemetery, Sydney. In Adelaide, I know where her parents' very modest grave is. I have quite a bit of material on her, if you are interested.
In SA we have a memorial to a phoney Titanic victim called Alan McRae. That remains a mystery. Its on this site.
Andrew Rogers has been researching the Aussies for some years and may have material that he's never shown me. A possibility for some kind of monument might be Donald Campbell, who came from Geelong. With the exception of Arthur McCrae, Charles Dahl and Evelyn Marsden, the Aussies are pretty obscure people.