Oldboy - 2003, Park Chan-Wook

this one shot scene is from one of my favorite films of all time, Oldboy. It took 17 takes to perfect it. Not only is this a great scene for its long shot (which is actually two scenes pieced together with clever editing), it is also an incredibly realistic fight scene.  loads of bad guys vs 1 good guy, love it.
And if you haven't seen oldboy, i suggest you do.