Twists I didnt see coming:
Wreck it Ralph
The Big Lebowski
The Dark Knight Rises
Inception didnt really have a big twist but it was definitely unpredictable and had a ton of little twists
Memento
Die Hard 1 and 3
Sense and Sensibility
American Psycho
Unbreakable
The Machinist
Twists I was able to see coming (but probably wouldnt have if I saw it when it came out) but still enjoyed:
Fight club
The Sixth Sense
Pride and Predjudice
Witness for the Prosectution
The Dark Knight
Twists I saw coming and/or didnt impress me (though I still probably enjoyed the movie, the twist wasnt well hidden/presented)
Lucky Number Slevin
The Crying Game
The Usual Suspect
I am particularly of the firm belief that if at any time a character has a flashback either through telling a story or remembering something, the events filmed in the flashback should actually have happened unless the flashbacker is crazy and truly believes the events happened or its stated before hand that the events being told may be made up by the teller. Otherwise its just breaking the fourth wall to lie to the audience which is not tricking them at all. However I have nothing against a flashback that leaves out parts of what happened.