What a great question. There are many different types of organizations out there that focus on the environment and sustainability. Here is one example that I really like.
In the year 2000, a number of students who were taking course on the environment at Yale University decided to start a sustainable food project on campus. In time, they created a farm and started growing food for one of the colleges on campus - Berkeley college. They also made a composting facility where they took the extra food from the dining halls and used that waste for the sustainability of the farm. In this way, nothing was literally wasted.
In 2005, volunteers even built wood-fired hearth oven at the farm, made with reclaimed wood and stone, which is used as well. Again, this is another development in the area of sustability.
By 2004, twenty percent of all the food served in the dining hall came from that farm. The sustainability project still continues and it thrives. Moreover, with the rising costs of food, this project will prove to be beneficial in so many different ways.