Kick-Ass defending that guy seemed like A Crowning Moment of Awesome, but what really kind of hit me was the way the guy said "Thank You". I'm sure that's what made fighting worth while for Kick Ass.
Hit-Girl's final moment with Big Daddy as he dies
Their whole relationship throughout the movie(and comic) is adorable in a very Addams Family kind of way.
It's sorta lessened in the comic considering... you know, this line still chokes me up.
"I just lost my daddy, give me a hug already."
The music during the gun battle just prior as well - the action is her dishing out awesome, but the music is channeling Big Daddy's pride watching his daughter slaughter everyone.
Katie forgiving Dave for lying and letting him spend the night.
Even though Frank is a cold-blood killer, there are several moments where you can tell he really loves and cares about his son. Like when he thinks Chris died in the factory and their reunion hug. Just look at the relief on Frank's face when he sees his son is alive.