Roger Doiron's TED talk "My Subversive Plot" is pretty awesome. Check out the 20 minute video about gardening and our food supply! Roger is the founder of Kitchen Gardens International: a "non-profit community of people growing some our own food and helping others to do the same."
From the talk:
"Gardening is a subversive activity...Food is a form of power. And when we encourage someone to grow some of their own food, we are encouraging them to take power into their hands."
"Gardening is a healthy gateway drug to other forms of food freedom."
I only have one thing to add in response to his stats about the amount of food needed to feed the world, let's not forget that we already grow enough food to feed the world's rising population. Hunger exists due to problems of food access and distribution.