All seem to be posting from hollywood movies, but I feel there are special moments in hindi movies also.
To add my two cents:
Terminator 2: Arnold's thumbs up at the end of the movie.
Independence day: Actually there are couple of scenes I like most - (1) Bull Pullman's (US president's) speech to the Americans on 4th July before going into the final battle with the aliens. (2) The ending when the aliens got defeated and Jeff Goldbum's daughter or Will Smith's daughter says "happy 4th of july daddy". (3) The drunkard who crashed his own fighter plane (suicide mission) to the alien ship's main weapon just as it was about to fire to destroy their shield.
Basic Instinct: Sharon Stone's famous scene at the police station
Jurassic Park: Scene starting from when the tourists at the jeep could hear the t-rex coming (vibrations on the glass of water) when the electric fence failed.
Armageddon: Bruce Willis giving up his life on the asteroid to save mankind.
Hungama: Most of the comedy scenes with Paresh Rawal, Akshaye Khanna, Shakti Kapoor.
Lakshya: 1) Hrithik hoisting the Indian flag at the peak after the climax and his reunion with Priety Zinta. 2) Hrithik and team defeating the Pakistanis.
Golmaal: "Beta Ramprasad"..
Most comedy scenes with the great Utpal Dutt and Amol Palekar.
And many more.