For now here is one of my favorite scenes in a movie:
Mr. and Mrs. Smith - Shootut Finale
its not the full scene but its all I can find. I love the music and choreography

Yeah the way this part was directed and the music (the love theme as i call it) was done well.

There are a couple recent others,
Meet the foc.kers with Ben Stiller the parr where he is to board the airplane and the flight personel tells him to step aside sir even though there is no one else there.

300
The entire movie was good from the famous line THIS IS SPARTA!!! following the mighty kick
And the battles like this:
http://www.youtube.com/watch?v=PH0NYQcARks&feature=related

Matrix
Morpheus vs Neo. At this time there was nothing like it was gripping to watch and just well done.

so many classic scenes and yet few of them made this thread, here is one great memorable scene from goodfellas, i love it:

link

Reservoir Dogs

These long dialogue scenes are one of the reasons Tarintino is the best.
Opening Scene:
http://ca.youtube.com/watch?v=HXLVGarpTzc&feature=related

Names:
http://ca.youtube.com/watch?v=DvMam5wsZIk&feature=related

So sadistic
http://ca.youtube.com/watch?v=sn0My-cis_Q

TAXI - Opening

Seven: John Doe
http://www.ropeofsilicon.com/article/top_ten_movie_villains/3