Brainwashed Nightcrawler utterly curb-stomping the Secret Service to get to the President. Obviously it's not something he has control over, but it looks pretty cool. It's even backed up with Mozart's ''Dies Irae''.
The first time Wolverine stabs one of Stryker's soldiers right through the chest. Until that moment, a lot of people were expecting Movie Wolverine to be sort of like Animated Wolverine, who doesn't really do that to living people (and which he never really did in the first film). Once it became clear that this version of Wolverine had no problems slicing living opponents, fans could truly anticipate the badassery to come and get it when Wolverine roars into the mooks with an animalistic berserker fury.
When you attack a school full of innocent children you pretty much get what's coming to you...
This Troper, long a fan of Colossus, actually stood up and cheered when he put the two soldiers through the wall.
Siryn in the second one got a personal CMOA for this troper. Given that they didn't give a hint to her identity and the theater was a lot louder than normal, when she screamed for the first time, no one was ready. An entire room of people and the projectionist howling in pain in real life showed exactly how powerful she really is.
The faceless Mook gets one too when, with his eardrums still being fully assaulted, still has the strength of mind to aim his gun and fire, putting her out instantly.
Magneto making his escape from the plastic prison in X2. The little smirk on his face when he senses metal in range of his abilities for the first time in months, backed up by Ian McKellen's masterful dialogue delivery. A very squicky and highly memorable death, certainly one of the better Mook dispatches of all time.
Laurio: Have a nice sleep, Lensherr? Magneto: There's something different about you today, Mr. Laurio. Laurio: Yeah, I was having a good day. Magneto: [gets up] No, it's something else... Laurio: Sit down. Magneto: No. Laurio: [draws his club] I said, sit your ass down! [He starts for Magneto, who holds up his hand. Laurio stops forcibly] Laurio: [gasps] What are you doing? Magneto: Ah, there it is... [He lifts his hand, and Laurio lifts into the air] Magneto: Too much iron in your blood! [He draws a cloud of iron particles out through Laurio's chest, and squeezes them into a set of ball bearings. Laurio collapses.] Magneto: Mr. Laurio, never trust a beautiful woman. Especially one who's interested in you.
Nightcrawler saving Rogue when she gets sucked out of the jet in X2. And Magneto catching the entire thing just before it hits the ground.
For Mystique, when she infiltrates Stryker's base, kicks ass, and then flips them the bird as she slides under the blastdoors.
The bit where about a dozen heavily armed troops are stationed in front of a door to prevent Magneto from coming through. Before they even see him Magneto uses his control of metal to rip every pin out of the multiple grenades that each of these Mooks are carrying. Boom.
Rogue piloting the jet in X-2. Also, earlier, when she stopped Pyro (who was still her friend at the time) from rampaging.
Pyro's rampage, at least until it goes too far, is awesome in itself. Considering the one idiot cop overreacted and shot Wolverine, they had the beating coming.
Honestly, just the fact that a major studio made a blockbuster sequel that was not only good but many people view as even better than the original is a CMOA for Hollywood.