This is long presentation but you might like it:

Mark Shepard is probably my favorite permaculture speakers. He is one of those who emphasizes that food production systems must be profitable. Many people in permaculture are little bit too hippies and want to just "live with the nature" and don't build actual systems that produce environmentally friendly food profitably and long-term.

Oh yeah, and this is book is a must-read: Letter To A Vegetarian Nation: We Need Livestock For Sustainable Food Production And Environmental Restoration