"180° South" - About retracing a 1960's trip to Chile by two rock climbing friends who went on to found Patagonia and The North Face
"Exit Through The Gift Shop" - Amazing work by Banksy about the state of street art and those who attempt to commercialize it
"Crips and Bloods: Made in America" - About the context and history of gangs in LA
"Man on Wire" - The story of Philippe Petit, a tightrope walker who eventually walked across a high wire between the World Trade Center
"The Rape of Europa" - Explores the history of famous works of art in Europe during the 12 years of Nazi destruction
Baraka, if you want inspiration.
The Class (Entre les murs), not a documentary, but a hyper-real film about youth and the possibilities of education.
Seven Up!, as to what may come.
"Exit Through The Gift Shop" - Banksy fucks with everyone, and makes you appreciate just how brilliant he is.
"King of Kong: Fistful of Quarters" - If you think start up nerds think they are all that, you won't believe it when you see just how cocky former arcade game world champions can be.
"I Think We're Alone Now" - I wouldn't call it "great," but its definitely weird. It follows two unusual people who believe they are connected to Tiffany, the 80s singer.
I had no idea what it was about when I flipped it on, but it's a great hacker movie. The guy who trained Flipper is trying to save some dolphins from being killed in Japan, so he teams up with some folks from Industrial Light and Magic to rig a secret cove with all kinds of spying equipment to catch the guys doing it. Really interesting.
http://en.wikipedia.org/wiki/Mugabe_and_the_White_African
(Disclaimer: Nothing to do with hacking whatsoever.)
Dreams With Sharp Teeth, about and starring Harlan Ellison. Very interesting.
The Smashing Machine