I'm sorry but you can't be serious. Would you ask for a list of all the tourist attractions in Europe?
Try these tourism sites for ideas:
http://www.queenslandholidays.com.au/index.cfm
http://www.visitnsw.com/
http://www.visitvictoria.com/
http://www.discovertasmania.com/
http://www.southaustralia.com/
http://www.westernaustralia.com/au/Pages/Welcome_to_Western_Australia.aspx
http://en.travelnt.com/
4 months will be enough if you fly some of the long stretches. It depends how much you want to do. To 'see it all' I think you need closer to a year.
Here's a list of some of the best locations ( I can't possibly tell you all the tourist attractions they have!)
Queensland:
Cairns and the Great Barrier Reef, with the nearby Daintree Rainforest and Daintree River with crocodile tours
The Whitsunday Islands - many different coral islands ranging from small and romantic to action packed. Go diving or snorkelling.
Fraser Island - beautiful world heritage listed sand island
The Gold Coast - all set up for tourism, full of theme parks, animal parks, beaches and heaps more
The Sunshine Coast - beaches and rainforest
NSW:
Byron Bay - centre of alternative culture and hippies, beaches
Sydney - one of the most beautiful cities in the world, vibrant
The Blue Mountains - Australian bushland
Broken Hill - outback mining town
the entire coast line - beautiful beaches and beach towns all the way down
Canberra (not strictly speaking in NSW) - lots of museums and national buildings
Jenolan Caves - limestone caves
Victoria:
Melbourne - very cultural city with great shopping and arts, trendy cafes
the Great Ocean Road - spectacular views over the coast
Mornington Peninsula - wineries, national parks, little galleries
Phillip Island - penguin viewing and fur seals
the Goldfields - gold rush historical towns
Tasmania:
Cradle Mountain - scenery, hiking and wildlife including Tasmanian devils
Port Arthur - old convict prison site, very interesting and spooky
the Western wilderness areas and the Tarkine Forest
South Australia:
Barossa Valley wine region and many other wine regions
Kangaroo Island - penguins, sea-lions, wildlife and rugged coastal scenery
the Flinders Ranges - hiking and 4WDdriving, outback scenery
Coober Pedy - people live underground to avoid the heat
Mt Gambier - Blue Lake, sinkholes, feed the possums
Port Lincoln - dive with sharks, tuna farming, fishing
Western Australia:
Margaret River - wineries, beaches and scenery
Rottnest Island - cycle around amongst the quokkas which are cute little wallabies
Monkey Mia - interact with wild dolphins
Ningaloo Reef - coral reef
Broome and the Kimberleys - rugged outback scenery, famous Cable beach, pearling industry, strong Chinese influence
Northern Territory
Uluru - used to be known as Ayers Rock, Aboriginal culture
Kakadu - rugged outback tropical scenery, Aboriginal culture, crocodiles and tropical wildlife, wetlands
Alice Springs - deserts, Aboriginal culture
Where to go depends on what time of year you are coming. In summer (Dec to Feb) you are best to stick to the south as it's the wet (really wet) humid season up north. In winter (Jun-Aug) the north is fabulous and the south is rather cool and drizzly. Central Australia is best avoided in summer as it's very hot.
You can also go kayaking, hot air ballooning, camel or horse riding, surfing, fishing, scuba diving and heaps more in many places around Australia.
Hope this helps :)