Obviously I couldn't just pick one. Okay, I could pick just one, but I don't want to. :p
The synchronized fight in Evangelion with Shinji and Asuka.
Fight scene from Cowboy Bebop where some thugs think that Spike is Vicious.
Epic potato chip scene from Death Note.
There are more epic scenes I would like to show you, but sadly there are no clips of them on YouTube.