In terms of live-action scenes, the film "Doom" had a cool parody of the game in which the protagonist ran through the base, clearing out the demons in classic Doom style. I thought it was pretty bad-ass.
I never got into One Piece, it bugs me that a human (let's say, Zorro) can be so thoroughly crushed and still survive; by this logic, anyone can be a bad-ass; just add immortality, and viola!
A fight that was memorable for me was in One Piece when Luffy smashed Belamy's face in. It wasn't so much as a "fight" but the scene just made me feel like "Yeah! Take that!" kind of emotion.
I would have to say my favorite fight in anime is Asuka versus the EVA series in End of Evangelion. I can't think of any words to describe how awesome it is atm. Just look it up on YouTube :3
Some of my personal favorites are: Goku v.s. Vegeta in the Saiyan Saga at about the large beam struggle part, or when Goku fights Frieza as a Super Saiyan. I still get chills because of how badass that scene was :cool: