Forgive me if some of these were mentioned, but I just did a super fast scan of the last few pages, so maybe I missed the mentions of some of these. Here are a few off the top of my head:
Stevie I have mentioned this one before. This is the one that started my love for docs. I took it home randomly after I bought the video store and was looking at the doc section we had. Never really thought about watching them before so gave it a go. It's by Steve James, director of Hoop Dreams
Hot Coffee - yes, the McDonald's lawsuit. It will make you think, especially when you see the lady's injuries and hear what she was asking for.
Born into Brothels - I had just been to India, so this one effected me a bit.
American Movie - 2 good old WI boys chase their dream - to make their horror movie Coven
Capturing the Friedmans - surprised this hadn't been mentioned, but probably missed it.
Resurrect Dead: The Mystery of the Toynbee Tiles - random one I had hear about from a podcast that fascinated me.
Jesus Camp - Just scary
Deliver Us from Evil - Again, just scary
Room 237 - good not so much in that I buy into them, more just fascinated on the theories these wackos were coming up with about Kubrick and The Shining.
The Cove - a hard watch, but still great.
The Look of Silence - for those that saw The Act of Killing, Oppenheimer did a follow up too.
By far my favorite genre, as I never dislike any of the movies I see (besides the obvious skewed, one sided movies). Glad I saw this thread to get me even more in the mood to get back in the habit of watching docs.