The one I find the most memorable (and was deservedly mentioned many times here) was the Khan/Kirk space battle inside the nebula. Not only does it still hold up, but I'm not sure you could have a scene like that in a modern film.
I agree. I use the below image as my wallpaper, and every day I'm amazed at how well it holds up even after 25 years.
http://usera.ImageCave.com/rapidnadion/phaser-hit.jpg[/IMG
EDIT: After poking around the web some more, I found this interesting passage about the above shot. I knew about the big secondary hull model, but had no idea they created the phaser cutting damage with stop-motion animation.
**From [url]http://www.ottens.co.uk/forgottentrek/tmp_8.php**[/url]
[quote]In one of the most impressive scenes of the battle, the Reliant fires its phasers at the Enterprise "neck" section, cutting an enormous gash in the process. This shot was created using traditional stop animation techniques. Kenneth Ralston explained: "I had that section done as a wax piece and then painted it to look like the ship. Obviously, we worked out exactly how the camera was going to move. Then I just went into the wax version, and I would take little sculpting tools and rip stuff up and bend it around. We'd film that, then the camera would move whatever distance it would cover in one frame, and I'd sculpt some more damage. Then, on top of that, we did some animation of a laser hit sort of cutting into it, but if left a real cut-–a big scar [ . . . ]."
The damage brought onto the Reliant was even more severe, and involved making several separate sections. "One of the engine pods blows up," remembered Ralston. 'We couldn't blow up the whole pod for some reason, so I built a shape similar to it and it was more like glass blowing out of the warp nacelle. We shot that as a separate element and then printed that on top of the actual model fo the Reliant, with other pieces blowing off of it. Then, when the whole nacelle blows off, that was just a bunch of explosions and a separate arm that we shot using motion control.""[/quote]