Here's some of my more memorable ones:
-Ripley 'kitting up' while going down the lift towards the end of Aliens. The one time a hero actually comes prepared; instead of taking a pistol with 6 bullets, she's strapping an automatic rifle / grenade launcher onto a flamethrower. Nice work, girl.
-Willem Dafoe getting left behind in Platoon, the classic shot up of him collapsing after rushing the chopper. Chokes me up every time.
-Minigun scene in Predator. Awesome.
-Take your pick from Dr Strangelove. The Coke machine scene maybe as it's not as cliched as the War Room stuff.
-Terminator scene in the car after escaping from Arnie, where Kyle is telling Sarah about the terminator.
That Terminator is out there. It can't be bargained with. It can't be reasoned with. It doesn't feel pity, or remorse, or fear. And it absolutely will not stop, ever, until you are dead!
Fantastic emotion in that scene. Both the way it's delivered by Kyle and Sarah's final realisation about what she is up against.
-Bit of a cliche, but the 'poster' scene in Shawshank.
-The ending of Se7en is pretty cool - you kinda know what's coming, but you just have to keep watching.
-Rocky in training, culminating in the run up the steps. Gets the adrenaline flowing and almost makes me wanna get up off my lazy arse and do some excersise!