I was looking for last minute domestic flights when I stumbled across Virgin Australia's Happy hour sale.
There seems to be some good prices (some even better than advertised) e.g. Sydney - Melbourne one way for $99 during the July holidays (24 June - 31 July) even though the site advertised as 'from $112'.
Some other July flights:
Adelaide - Canberra from $155 (travel between 1 July - 18 August)
Adelaide - Coffs Harbour via Sydney from $199 (travel between 29 July - 26 September)
Brisbane - Rockhampton from $109 (travel between 1 - 31 July)
Cairns - Sydney starts from $175 (travel between 1 - 21 July)
Launceston - Melbourne from $82 (travel between 28 June - 31 July)
Melbourne - Perth starts from $229 (travel between 2 - 18 July)
Perth - Sydney starts from $229 (travel between 25 June - 10 July)
No Adelaide to Sydney