James Marsh (Man On Wire) delivers a solid documentary about a chimpanzee, and the people responsible for him being raised as a human... I won't tell you the rest: you'll have to see it!
Official Site: http://www.project-nim.com/

Documentary on young Black Panther leader cut down by Chicago Police in a hail of bullets while he slept. Essential. Don't expect any narration: the footage speaks for itself.

High drama, fascinating documentary about a Lioness, her cubs, and the struggle for survival. Beverly and Dereck Joubert deliver a heart wrenching and beautiful film. Jeremy Irons narrates.
http://movies.nationalgeographic.com/movies/last-lions/

Incredibly awesome Swedish documentary about the Black Experience. Features a  jailhouse interview with Angela Davis. Can't wait to see it again!
Official Site: http://blackpowermixtape.com/

Errol Morris (The Fog of War) specializes in subject driven documentaries.  A self-absorbed "beauty" becomes obsessed with an average Mormon dude, and a media frenzy ensues. Kinky.
Official Site: http://www.ifcfilms.com/films/tabloid

Werner Herzog has access to the most interesting material, (Encounters at the End of the World, Grizzly Man,) and able to insert himself into his documentary films in a delicate manner. He's well suited to explore and share the world's oldest known paintings in the Chauvet Cave of Southern France.
Official Site: http://www.ifcfilms.com/films/cave-of-forgotten-dreams

Man, play, movie, movement, milieu. Documentary about the journey of the groundbreaking play: The Boys in the Band.  Mart Crowley was a failed playwright, and a close personal friend of Natalie Wood. Fascinating look at how he turned it around with a little help from his friends, (and William Friedkin.)
Official Site: http://firstrunfeatures.com/makingtheboys/

Once a film is deemed a national treasure, does the filmmaker have the right to alter it? I think not. George Lucas and Star Wars is the topic of this fan driven awesome documentary. Love it!
Official Site: http://www.peoplevsgeorge.com/

Yes.
Official Site: http://www.buckthefilm.com/

Beautiful documentary from Patricio Guzmán about the simultaneous quest of astronomers for the origins of life in distant galaxies, and archeologists and mothers search for the remains of The Disappeared in Chile's Atacama desert. Cinematic, moving.
Official Site: http://icarusfilms.com/new2011/nost.html