James T. Kirk:
“We’re sending it over now, Khan!”
Predator: The only one left alive, Arnie makes and sets his traps, cakes himself in mud, then stands atop a fallen tree bridge, holds aloft a torch and emits a blood curdling animal roar challenging the Predator.
Most Jackie Chan martial arts films have one or two of these moments. My favorite is the master of hands/master of feet fight at the end of Who Am I?.
How about the highlight of Gladiator?
My name is Maximus Decimus Meridius. General of the Roman Legion, Commander of the armies of the North, and servant to the true emperor Marcus Aurelius. Father to a murdered son, Husband to a murdered wife, and I will have my vengeance … in this life or the next.
(I might have messed part of that up)
Damn that part rules.
Any Bruce Lee movie (although I’m thinking of Enter the Dragon) when Lee is wounded, tastes his own blood, then goes into controlled berserker mode.
—Opening night of X-Men. Cage match. Ripped guy, back to camera, hardly even in the shot, but everyone knew that HAD to be Wolverine!
—Opening night of Titanic. Rose spitting in Cal’s face.
—Fight Club. I sulked through the first ten minutes, having wanted to see Three Kings, and also having been misinformed as to the movie’s theme. Was expecting some Good Will Hunting-esque trip (for some reason), and opening scenes failed to reassure me.
Then.
Edward Norton’s droning speech is interrupted by the bone-shaking thud of a mid-air jet collision. Engines scream, wind howls, fuselage tears off, while Norton continues to stare impassively. Ding! Calm again, except that Brad Pitt is now on screen, growling softly.
—The Fly (1986). Mall cinema. First time Jeff Goldblum faced the camera, everyone went “ooooooohhhhh!”, knowing that this was going to be twisted; it had to be!
DIE HARD: The scene when Willis hands Rickman (talking with an American accent) a gun and turns his back on him…
ST: First Contact: Data to Borg Queen: Resistance is futile.
MEMENTO: when the hero finds out the truth
CASBLANCA; Bogie’s speech to Lazlo at the airport
VERTIGO: The moment in the car when Scotty looks over at the woman and we know he knows the truth.
Z: The prosecutor, who has carefully corrected everyone who called the death a murder - “the incident” - accidentally calls it a murder and we/he know that he has changed his mind.
and, of course:
PRINCESS BRIDE: Inigo: Hello! My name is Inigo Montoya! You killed my father! PREPARE TO DIE! (Count Rugen: Stop saying that!)
ABOUT A BOY: (SPOILER WARNING@!!!)
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The mother essentially accuses the hero of being a child molester. He tells her flat out that the boy has been coming to him because he’s miserably unhappy. She mentally spins 180 degrees on a dime and demands to know what he is going to do to solve her son’s problem. Breathtaking.
Fifteen Iguana
My favorite “woo hoo” moment is the last couple of minutes of the Stones’ Sympathy for the Devil. 
Erin Brokovich - that bit where the snooty lawyer tells Erin her files are ‘incomplete’, and Erin subsequently lists off the names, relationships, phone numbers, and ages of a bunch of the plantiffs. [sub](Incidentally, I saw the real Erin Brockovich speak a couple of months ago…she acts a lot like Julia Roberts)[/sub]
chique, are you sure that’s not the other way around?
A couple of my favorite woohoo moments are from Babylon 5, one where Delenn says something along the lines of, “He is behind me, you are in front of me. If you value your lives, be somewhere else.”
And Ivanova’s Who am I? I am Susan Ivanova. Commander. Daughter of Andre and Sophie Ivanov. I am the right hand of vengeance and the boot that is going to kick your sorry ass all the way back to Earth, sweetheart. I am death incarnate, and the last living thing that you are ever going to see. God sent me."
There’s more, but those are the two that pop into mind immediately.
Also, the part in Mad Max when Max steals the V8 Interceptor and goes to hunt down Toecutter and his gang. You just know it’s going to be good. And Mad Max II (Road Warrior) when Max drives the tanker truck out of the compound for the final confrontation with the bad guys. Pity the bad guys.
Dead Poets’ Society
“O Captain, my Captain!”
You know what I’m talking about.
Yippe-Ki-Yay, Motherfucker.
It don’t get any better than that.
The Matrix was more or less one continuous woo-hoo moment.
Or in T2:
Conner: Remember, don’t kill anyone.
Arnie: [Shoots guard in kneecap] He’ll live.
…we have a full tank of gas, a half pack of ciggarettes, it’s dark, and we’re wearing sunglasses.
Hit it.
And the last chase in The Blues Brothers begins.
Yes, yes, these all rock.
Three more I like. Two from Die Hard , the final little touch that just made the movie for me: “Now I have a machine gun. Ho, ho, ho.” And the part where they finally open the big vault. That whole scene is priceless.
I also like Silence of the Lambs , where Starling first meets Lecter. She’s walking in to see him, and he’s just standing there, watching her come in and in total control of his world.