Killing our nascent Fibre-to-the-Home rollout which had just begun after years of planning by the previous government. We now use problematic mish mash of slow copper instead of fibre (Murdoch wanted this so Tony gave it up for him).
Killing the mining tax for his donors. This would would have returned billions for our country. We could have begun a sovereign wealth fund like Norway who have over $1 Trillion in theirs. Australia also makes minimal profit from gas exports. Qatar exports less than us but their country profits 2600% more per year than Australia.
Domestic buyers on the east coast of Australia now pay one of the highest prices in the world for gas. Double the price our exporters are buying it for (and they have liquefaction and transport costs included).