HERE HERE kmg365!! Along Came A Spider had the best twist EVER and of course, I never guessed it. A MUST see! 
Along Came A Spider
Yes, I’ve got the videos of ‘House of Cards’, which is probably where the slip originated.
Now what was Urquhart’s catch-phrase?
The original Dutch version of The Vanishing (not the same director’s Hollywood remake).
I’ll second Diggstown (one of my ALL TIME faves!), and add Shattered, starring Tom Berenger.
Vertigo had a mind-fudge ending to behold. Then again, Hitchcock’s movies seemed to all have a great ending, often with surprises that hit you on the blind side.
And if you like The Sixth Sense, you may also like The Others or The Ring, both of which had kooky endings.
Terry Gillam’s Brazil has two endings (or at least you think it is ending, then it goes on some more - the first one is a classic happy ending, the second is more realistic.
I’ve recommended these many times:
Charade – wonderfully twisted plot. Script by Peter Stone. Directed by Stanley Donen http://www.imdb.com/title/tt0056923/
Great romanic comedy/thriller with Cary Grant and Audrey Hepburn as the leads. Ignore the remake The Truth About Charlie
Mirage – A lot of the same folks involved as in Charade – Stone’s back, as are Walter Matthau and George Kennedy. But this time it’s played much darker. Gregory Peck plays the lead, a man with amnesia who finds that the world doesn’t resemble what little he can remember. http://www.imdb.com/title/tt0059448/ They tried to duplicate the success again with Arabesque, but it didn’t work out.
The Last of Sheila – my all-time favorite movie mystery. They play fair and give you all the clues (not to mention a lot of hints), but I’ll bet you still don’t get the solution. Lots of twists, and they flow naturally from the situation. Written by Stephen Sondhein and Anthony Perkins (Norman Bates!!). Highly recommended. http://us.imdb.com/title/tt0070291/
Body Heat – Written and Directed by Lawrence Kasdan. William Hurt. Kathleen Turner. Great and unexpected twist. http://us.imdb.com/title/tt0082089/
The Flight of the Phoenix – Offbeat film, with a twist near the end to add a little spice. http://us.imdb.com/title/tt0059183/
The Odessa File – All of Frederick Forsyth’s early books have twists in them, but not all were filmed, and in Day of the Jackal the two twists aren’t given much weight. But the twist in The Odessa File is pretty central, and comes as a surprise. http://us.imdb.com/title/tt0071935/
Sleuth – Anthony Shaffer’s adaptation of his play has a lot of twists, buried in a plot that addresses the assumptions and conventions of mystery books and plays. After you’ve gone through a couple, you find yourself wondering if he’s going to throw in another twist , or not. http://us.imdb.com/title/tt0069281/
Oh, heck – how can I forget this one. Alfred Hitchcock generally didn’t use twists – he’d rather you watched everything unfolding onscreen in full knowledge. The main characters didn’t know it, but you did, and that’s what made you squirm. So he’d reveal everything early on. But one film reserved a twist until the end. If you haven’t seen it, go rent Psycho before anybody spoils it for you.
The Others, starring Nicole Kidman.
And I’d second Wild Things. That one is sheer entertainment from beginning to end.
I’d say The Ring has a darn good twist to it, too.
The Italian Job
Heist
Bandits
All are group criminal activity jobs… but you probably figured it out.
In the same vein, Nine Queens (Spanish subtitled).
Also:
Lock Stock & Two Smoking Barrels,
Steam (Italian/Turkish subtitled),
Jacob’s Ladder and
Funny Games (German subtitled).
**Dressed to Kill**
and
Body Double
I’m a HUGE fan of this genre, so thank you to the originating poster for starting this thread!!
Let me throw my votes in for:
The Game
A Perfect Murder
Signs
Sixth Sense
Memento
FALLEN
I Wake up Screaming - a lesser known film noir with Victor Mature, Betty Grable, and Laird Cregar.
Unfortunately, though I’ve never seen Psycho, I know that the mother’s actually dead.
Not sure if that is the big surprise or not.