My personal list:

Citizen Kane (1941) 
2001: A Space Odyssey (1968) 
Solaris (1972) 
Persona (1966) 
M (1931) 
Metropolis (1927) 
Harvey (1950) 
Fail-Safe (1964) 
The Great Dictator (1940) 
Seconds (1966) 
Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb (1964) 
The Pawnbroker (1964) 
The Seventh Seal (1957) 
Giant (1956) 
12 Angry Men (1957) 
Stalker (1979) 
Rope (1948) 
Repulsion (1965) 
The Grapes of Wrath (1940) 
Catch-22 (1970) 
What Ever Happened to Baby Jane? (1962) 
The Hill (1965) 
Judgment at Nuremberg (1961) 
Monsieur Verdoux (1947) 
The Maltese Falcon (1941) 
Dead Man (1995) 
The Getaway (1972) 
Chinatown (1974) 
Who's Afraid of Virginia Woolf? (1966) 
Brazil (1985) 
Harakiri (1962) 
Vertigo (1958) 
Manhattan (1979) 
The Searchers (1956) 
The Hustler (1961) 
Casablanca (1942) 
Seven Samurai (1954) 
Rebel Without a Cause (1955) 
Eraserhead (1977) 
Blowup (1966) 
Once Upon a Time in America (1984) 
The Great Escape (1963) 
Brick (2005) 
The Apartment (1960) 
The Truman Show (1998) 
The Tree of Life (2011) 
Gravity (2013) 
Moonrise Kingdom (2012) 
Double Indemnity (1944) 
Inception (2010) 
The Godfather (1972) 
Lolita (1962) 
Memento (2000) 
Adaptation. (2002) 
The Departed (2006) 
Rosemary's Baby (1968) 
The Deer Hunter (1978) 
Ed Wood (1994) 
Network (1976) 
The Philadelphia Story (1940) 
Drive (2011) 
Annie Hall (1977) 
The Man Who Shot Liberty Valance (1962) 
The Wild One (1953) 
The Glass Key (1942) 
Eternal Sunshine of the Spotless Mind (2004) 
Obsession (1976) 
The Assassination of Jesse James by the Coward Robert Ford (2007) 
Fury (1936) 
Ran (1985) 
The Americanization of Emily (1964) 
The Wrong Man (1956) 
To Kill a Mockingbird (1962) 
The Cremator (1969) 
To Catch a Thief (1955) 
The Fighter (2010) 
Inglourious Basterds (2009) 
A Face in the Crowd (1957) 
The Intruder (1962) 
Charade (1963) 
Sunset Blvd (1950) 
Heat (1995) 
Fargo (1996) 
Cross of Iron (1977) 
The Big Heat (1953) 
Alice Doesn't Live Here Anymore (1974) 
Fear and Loathing in Las Vegas (1998) 
The Haunting (1963) 
Gone Baby Gone (2007) 
The Killing Fields (1984) 
High Fidelity (2000) 
The Green Mile (1999) 
The Hanging Tree (1959) 
My Life to Live (1962) 
The Face of Another (1966) 
The Trip (1967) 
Splendor in the Grass (1961) 
Woman in the Dunes (1964) 
The Silence (1963) 
Dead Poets Society (1989)