I think that's what non-Australians call it, here it's called preferential voting. Basically you don't just vote for one candidate, you rank them in order of preference. When they count the votes, first they simply count everyone's first preference (just like a normal election), and rank all the candidates. If no one candidate has enough votes to be clearly the winner they take the least popular candidate, eliminate him or her and distribute the second preferences of the votes cast for him/her. Then they re-rank everyone and see if there is a clear winner. This continues until there is one.Stompwampa said:instant runoff voting?
The idea is that even if you vote for a minority party your vote isn't wasted, your preferences still have a chance of making a difference. It's designed to reduce the whole "wasted vote" thing minor parties have and give them more power. It also has the nice side effect of encouraging all the parties to negotiate with each other for each others' preferences (the major parties give out slips with their recommended preferences on them, many people follow this rather than go to all the trouble of ranking all their preferences, which can be quite a lot).
Doesn't really work though. Mostly due to voter apathy, it's all their bloody fault.