Whether it be horror, action, drama, romance, sci-fi, or comedy what is it?
The Tears in Rain scene at the climix of Blade Runner captivated me. To have the in human cyborg killer at the very end say so few words that carried so much humanity was mind blowing to me.
Let this serve as direct evidence that Tom Cruise can act.
Outside of excellent dialogue and acting, on terms of intensity and fun, I'd go for the intro of Raiders of the Lost Ark. That entire sequence was awesome.
http://www.youtube.com/watch?v=Kcl6fiShbzE - I dunno, just felt like "It's easy to paint someone as a monster without looking under the paint to see a human".
The Cube - When Worth proposes his idea for why they're there and what it is. It's shocking when the most absurd makes the most sense.
Indiana Jones shooting the swordsman - https://www.youtube.com/watch?v=7YyBtMxZgQs
Fun fact, that was completely unscripted. They were actually supposed to do this long drawn out fight scene but in one take Ford pulled the pistol and shot him and he quickly fell to play along with it. The crowd then also went along with it and cheered. Spielberg loved it so much he kept it.