Naruto vs sasuke at waterfalls. It was the it was such an epic fight, the anime couldn't possibly make any fights better and so they all began to suck.

trigun - knives vs vash
bebop - spike vs vicious
champloo - mugen vs sara
gungrave - brandon heat vs bunji
shootfighter tekken ova - all of em
tengen toppa gurren lagann - all of em

"Hip-hop was set out in the dark. They used to do it out in the park"

History's Strongest Disciple Kenichi:
Kenichi vs. Odin

Yu Yu Hakusho:
Yosuke (demon form) vs. Sensui

Mahou Sensei Negima:
Negi Springfield + Kagurazaka Asuna + Miyazaki Nodoka vs. Inugami Kotarou
Negi Springfield + Kagurazaka Asuna vs. Fate Averruncus
Negi Springfield + Inugami Kotarou vs. Graf Wilhelm Josef Von Herrman + Slimes
Kuu Fei vs. Tetsumiya Mana
Negi Springfield vs. Takahata Takamichi
Negi Springfield vs. Sakurazaki Setsuna
Nagase Kaede vs. Albireo Imma
Negi Springfield vs. Chao Ling Chen
Negi Springfield vs. Kagetaro (Shadow Man - recent chapters)

I like to see Berserk as a huge action scene 😀

[img]http://www.freewebs.com/majormarmot/hypnosis%2Dss.gif[/img]
THIS POST DOES NOT EXIST......IT'S ALL IN YOUR IMAGINATION

Most of those in Rebirth. Soooo many mangas need to take pacing lessons from this one.
I tend to find many fights stretching out far more that they should (to the point I just randomly flip pages) but those are "ZOMG" even without ridiculous amounts of chapters per fight or number of power-ups. Especially the ones in the tournament.
Forgot Fairy Tail. And D.Gray-Man. Not an exact action scene, but overall the style of fighting was really interesting.

it would have to be kenpachi and ichigo. i liked it. it showed power and strength.

Any action scene in Dogs: Bullets and Carnage simply rawks

Wow. So many to choose. Here goes:

1. Luffy vs Crocodile
2. Luffy vs Rob Lucci
3. Luffy vs Arlong
4. Ichigo vs Kenpachi
5. Ichigo vs Grimjaw
6. Ichigo vs Byakuya
7. Kenpachi vs Tousen + Komamura
8. Kenpachi vs Noitora
9. Jiraiya vs Pein
10. Gaara vs Kimimaro

[img]http://i590.photobucket.com/albums/ss350/afikolami/untitled3.png[/img]