Man, there are a helluva lot of great flicks mentioned here. In particular, I'll second:
The Fog Of War - McNamara is sharp as a tack, Morris's visual style is excellent, and the results are gripping and positively haunting. The best documentary to come down the pike in ages - this is crucial viewing.
Hearts and Minds - This is not an unbiased film, nor is it trying to be. This is an impassioned argument against American involvement in Vietnam and it is not pretending to be anything otherwise. Do not let this stop you from watching it, because this is one hell of a flim, with astonishing footage, hard questions, and brilliant editing.
The Power of Nightmares - A scathing British television documentary about the rise of the neoconservatives in America and their involvement in current Iraq policy. Again, this is not a film that is trying to be unbiased, but that's part of what makes it great. And, despite the grim title, parts of The Power of Nightmares are very funny, in a particularly black humor sort of way. Fascinating viewing. While not currently available on DVD, it should be available for donwload online without much difficulty.
Koyaanisqatsi - This is the sort of film you will either love or hate - an abstract argument that modern society is out of tune with nature, told without any narration or dialogue whatsoever, using high-speed and slow motion footage set to a hypnotic (or, if you're not a fan, "irritating") Philip Glass score. Okay, so the movie isn't really saying anything you probably didn't already think about yourself from time to time, but it's visually stunning, with an astonishing 20-minute finale followed by a harrowing epilogue.
Finally, here's a recommendations of my own:
The Atomic Cafe - Easily my favorite of all the atomic bomb films, The Atomic Cafe provides a picture of American Cold War fears told entirely through period newsreals, television clips, propaganda films, and government footage of atomic testing. This sounds dry but thanks to brilliant editing the result is fascinating and darkly humorous; for example, a segment about the Bikini Atoll tests shows repeated takes of a propaganda film celebrating the (involuntary) handover of the Island to the Americans, concluding with newsreel footage of the islanders singing "You Are My Sunshine" counting down to the test itself. In addition to plenty of test footage, crude propaganda, and shockingly ignorant statements by public officials, the film is full of glimses of popular culture of the times. In particular, the soundtrack is a hoot and a half, playing period songs about the bomb; my favorite is
"Jesus Hits Like An Atom Bomb", as recently covered by
the Blind Boys of Alabama. If nothing else, you've got to appreciate a film that digs up the W.H.P. Blandy quote, "I am not an atomic playboy". And, yes, all of Duck and Cover is included.
FnordChan