I myself have been fortunate enough to see Jacob Holdt's three-hour slideshow presentation of his book, American Pictures. I'm not a sentimental person, and don't often find myself being really moved by things that doesn't affect me directly, but this show really took us all through every emotion. Half the room was in tears when the light was turned back on. You may or may not agree with Holdt's opinions, but they really aren't essential to the show. What is essential is raising consciousness.
If you won't spend money on the actual book, at least check out the web-site at www.american-pictures.com. It's available in both English and Danish.