[YOW][1] has been the one I've attended the last 2 years, and they are normally in 2 out of three of Brisbane, Sydney & Melbourne. It's been around for 3 years now. 

The conference is multi-disciplinary and covers tech as well as process, inviting speakers from the Java, .NET, Ruby, Erlang and anything else. 

It's pretty big and backed by [Dave Thomas][2] and has some fantastic speakers every year. 

They also run YOW nights throughout the year, which are just small one or two person talks which usually coincide with that speaker's travels.  

[Edited]

I forgot to add that the YOW conference is the Australian version of the [JAOO][3] conference which is held in Europe. 

  [1]: http://yowconference.com.au/
  [2]: http://www.davethomas.net/index.html
  [3]: http://gotocon.com/aarhus-2010/