Yeah, I would have to agree with Forbidden on that one, when Edward Norton tells that black guy to kiss the curb, then just stomps of the back of is head. Just thinking about it makes me shivver a bit. There's a lot more, like War movies, but that one comes up all the time.
The scene in the Chronicles of Riddick where the man just walks to his death in that scortching heat. That had shivers running down my whole spine and I actually shedded a tear for him ;_; That I say is a must see scene.