Work Exchange Opportunities
In Australia you can find businesses that are willing to provide accommodation and food in return for working a few hours a day. This is an awesome chance to do something different on your trip whilst helping at a grass roots level.
Willing Workers on Organic Farms is an international program geared towards spreading the joys of organic farming. They sell a book which lists organic farms and organisations across Australia where you can get free food and lodgings in return for working 4-6 hours a day. For more details see their website
This international organisation helps to coordinate work exchange in all areas of commerce, including farming (organic and non organic), homestays, hostels and more.