An interesting new website is HouseNet -- a social media site for property people. The cost ranges from nothing to $79 a month, depending on what you want to use the site for. The site is promoting itself as a replacement for Domain and RealEstate.com.au.
As an aside, RealEstate.com.au only takes listing from real estate agents. If you are looking to rent, then don't forget to look at Domain.com.au, which also takes listings from private individuals. So there are different opportunities available on Domain.