I found this link on the Whole Foods newsletter I receive. It is a listing of food-based documentaries that are available and where they are showing around the country. If you are not nearby, many of them are available for purchase. We own King Corn and Food Inc.
I am guessing that many of the other ones (excluding the brand new releases) are probably available from Netflix. We got The Future of Food last Friday from Netflix, but haven't had time to watch it yet.
We will be seeing a preview of Farmaggedon in Madison, WI in about 10 days.