The Socialist Alliance was formed in 2001 as a merger of a number of socialist groups. As the name suggests they advocate socialist policies for Australia.
On social issues I find them to be quite strong. Equal rights for all including gay marriage, better treatment of refugees, more funding for public transport and making it free to use, a strong commitment to the environment, stronger unions and greater worker's rights.
Part of their plan for achieving a lot of this though is to nationalize a lot of industries. Mining, steel production, farming, and more. I'm generally supportive of state run enterprises, but in situations where market failures make it appropriate, such instances of natural monopolies (such as electricity distribution) or where free rider effects and information mismatches prevent an informed market forming (such as healthcare). For the production of pretty generic and standard items such as food and steel, there is no such need. And saying we should nationalize them to reduce carbon emissions, I think having the government set up some ground rules via a carbon tax is a better way to go.
Overall, I like want they want to achieve, but not the methods. This is a step up from most parties where I don't like what they want to achieve or how they want to do it.
Socialist Alliance has senate candidates in New South Wales and seven candidates around Australia for the house of representatives.