Fast times at Ridgemont High, Pheobe Cates pool scene. "Moving in Stereo"

And the "WELL ... DUH" Award goes to...

E.T. The Extraterrestrial - The "I'll be right here" moment. John Williams' magnificent score punctuates this scene perfectly.

Gladiator - The scene in the forest battle when Maximus leads the charge through the trees. Hans Zimmer's thundering score is just awesome. The moment when his dog leaps through the fire is the coolest part.

The Matrix - The slow-mo shot of trinity being chased by the agents on the rooftops. Don Davis' frenetic score compliments the scene masterfully.

The Matrix Reloaded - The scene where Neo restarts Trinity's heart. The finest emotional moment in the entire trilogy.

Empire Strikes Back - The scene where Luke is hanging at the bottom of Cloud City and he calls out to Leia. John Williams proves he is the best there is with the powerful "Force" theme.

Drop Zone - The scene where the Kid's parachute malfunctions, and the guy who barely talks, jettisons his own parachute and goes into an almost superman-like free-fall to rescue the kid. Hans Zimmer's awesome fast-paced score(the one that is used in alot of trailers like The Mask of Zorro.) is a bright spot in an ok film.

X-Men 2 The opening scene where Nightcrawler does that floating roundhouse kick that knocks out a Secret Service agent as Mozart plays in all its glory.

Transformers: The Movie:
Optimus Prime - Megatron must be stopped, no matter the cost - Stan Bush - "The Touch" starts playing...

Hot Rod & Daniel driving to Autobot City - Stan Bush - "Dare"

Hot Rod opening The Matrix at the end of the movie and Stan Bush's "The Touch" playing again...

From the moment Vader hacks off Luke's hand to the end of the credits, this is my all-time favorite scored portion of a film. It's why I hate the SE so much. Lucas butchered Williams' work with a bunch of unnecessary additions(plus he took out "Bring my shuttle!").

A few others:

"We Have All the Time In the World" in On Her Majesty's Secret Service - A love montage in a Bond movie is a strange thing to see, but Louis Armstrong's song makes it work.

Jamiroquai's "Canned Heat" in Napoleon Dynamite - No explanation necessary. If you've seen the movie, you know how bizarrely cool this scene is.

I would have to say that Wes Anderson takes the cake in this category. It seems that he builds scenes around the music instead of the other way around. One of my favorites is "Me and Juilo down by the Schoolyard" while Royal and the boys are out causing mischief.

I second this scene

the music during the asteroid/chase scene in Empire Strikes Back is terrific.

John Travolta walking to STAYIN' ALIVE in SATURDAY NIGHT FEVER.

Yeah, I remember that thread. Nobody agreed with me there, either.

Scarface (1983)
The montage of rising power with Pushing to the Limit playing, the apex coming at Tony's wedding.

Definitely!!!

If I didn't include Transformers then a couple I like are:

At the end of The Lion King as Simba is climbing Pride Rock during the rainstorm and the instrumental song kicks in.

The scene in Collateral when the coyotes cross the street. I think the name of the song that's playing is Shadow on the Sun by Audioslave.

Pam Grier coming out of prison to meet Robert Forster to "Natural High" by Bloodstone, in Jackie Brown

basically anything from Jackie Brown.

Most of the scenes I think of are with scores or orchestral music, not with songs.

The ending of Gallipoli, to Albinoni's Adagio

The use of Samuel Barber's Adagio for Strings in Platoon

The escape sequence in Aliens to Jame Horner's score.

The battle of the mounds sequence in Conan the Barbarian (Basil Pouledouris' score).

The use of the many versions of "Blue Moon" in An American Werewolf in London, especially for the main transformation scene and the ending credit transition.

The whole creation of the Requiem mass sequence in Amadeus.

The transition between the adagio and rondo of Beethoven's 5th piano concerto at the end of Immortal Beloved was masterful timing.

The use of "A Mi Manera" by The Gipsy Kings in the finale of The Heist (the Pierce Brosnan film).

The use of "Surfin' Bird" in Full Metal Jacket. Also the transition to in country using Nancy Sinatra's "These Boots..."

Brian Eno's Needles in the Camel's Eye at the beginning of Velvet Goldmine

Joe Walsh's In the City at the end of The Warriors

and many many more I cannot think of at this time...

I actually think Tarantino uses music better than anyone, but the scene I remember was the house burning scene in Badlands. I thought it was the best use of music I have seen. And Excalibur, which is helped by using the best (O Fortuna) and one of the best (Siegfrieds Funeral March) pieces of music ever written. I searched for the soundtrack for years before being told what they were.

Magnolia Near the end where the cast sings along to Aimee Mann's Wise Up