WWOOF, formerly known as Working Weekends On Organic Farms, then Willing Workers On Organic Farms, but currently stands for World Wide Opportunities On Organic Farms. It started in England in 1971 and has been gaining popularity around the world ever since. In exchange for learning experiences, food, and shelter (though this is flexible and many farms ask volunteers to bring their own tents) WWOOFers voluntarily work on organic farms or ecological building projects. You can WWOOF on your neighbor's farm or you can WWOOF on the other side of the world. There is often an element of cultural exchange as well as agricultural. It allows city-dwellers to experience a different lifestyle and deepen their understanding of their food sources, potential farmers to "test the waters" and gain ideas, and current farmers to see different types of farms and methods.

Terra Preta, or "Dark Earth" is the name for the super-fertile, man-made soil, covering a combined area, the size of France, that has been discovered in the Amazon. The above video and it's accompanying article at 
http://news.nationalgeographic.com/news/2008/11/081119-lost-cities-amazon.html  gives an excellent synopsis of what it is, and why it's such an incredible and significant discovery.

Terra Preta is now being intensively studied as a hopeful solution to the impending climate and agricultural crises.
 Terra Preta seems to have many ingredients that seem to act synergisticly, but the key ingredient is charcoal. Below is an excellent video on how to make your own charcoal, in a non-polluting way, on a family garden-sized scale. The finished charcoal is ground up, and moistened, and mixed 50/50 with compost (and other needed soil amendments), and then it is tilled into the garden soil.