Power League is an interesting concept. It provides free access to its site which is based on the idea of leagues. Leagues are forums or discussions about particular topics; students can discuss, question, debate and even vote. If a league is not suitable or available, teachers can start their own league.
Power League is a way to get students actively engaged in topics quickly and easily as they can all have their own say and opinion and vote on the topic, whereas in class, there are often students who are reluctant to voice their opinions.
Although designed in the UK for Key Stages 3 and 4 (years 7-9 and years 10-11), Power League is a very useful site for Australian teachers and is ideal for debating or any class that requires discussion. This teacher guide will give you much more information.