I don't know about Australia, but in the US, there are dozens of reputable schools offering a variety of online aviation degrees, from associates degrees through masters degrees.
AOPA has compiled the information in a single, easy to read, online document.
Flight Training: 2011 Flight Training College Directory
ERAU is definitely one of the more well known schools because the main focus is aviation. There are many other great programs that are part of a larger University such as University of North Dakota, plus many smaller programs.
ERAU is also at the high end of the price scale. You can get the same for less at other schools.