Greatest Musical Moments in Film History

Step Into Liguid, "Glassier and Glassier"

Wow, really good calls folks! Here's a few I didn't catch listed (sorry if repeating):

Amadeus - Mozart dictating "Reqiuem" to Salieri - you can faintly hear "Reqiuem" popping up in snippets in the background
Heat - Al Pacino driving after Robert DeNiro on the highway - it's just downright cool
Reservoir Dogs - Opening Credits - "Little Green Bag"

I just want to add to this list:

Superman: opening credits, Krypton establishing shot

Raiders: Map room scene

Dr. No: First occurrence of the James Bond theme in all its jazzy glory

Apollo 13: opening credits, launch

Aliens: escape from planet, climax in airlock

Gladiator: first gladiator battle in Rome, Maximus' reveal to Commodus, death scene

The Village: Joaquin pulls Bryce into the house, the vote at end

And from Star Wars:
II: Obi-Wan v. Jango
III: recut of duel music from ESB when Yoda confronts Sidious, funeral music, binary sunset
IV: Assault on Death Star
V: Duel w/ Vader (Used in EpIII)
VI: Climax of duel, SE celebration

The Star Wars opening text scroll in ANH.

It's not a movie, but one of the most iconic moments in television history is in the pilot of Miami Vice when Crockett and Tubbs are in the Spyder on the streets at night and Phil Collins In The Air Tonight is playing.

Darth Maul apearing in theed.

fliyig over jurasic park island

opening sequence of all star wars films

Another on of my favourites:
The very end scene of Dragon: The Bruce Lee story when the love theme cranks as Bruce is shadow boxing in front of the huge sun behind him.

Battle of Yavin's "Use the Force, Luke!" moment. That scene would not work without that music, yo.

Luke's arrival in Cloud City in "Darth Vader's Trap."

All of the "Battle of the Heroes" cues work better as film moments than do the "Duel of the Fates" cues, which are a little more effective as music-only.

In Aliens, Ripley's ride down the elevator and the heroes' escape from the explosion are the best work James Horner's ever done.

Well except maybe the entire "Battle in the Nebula" and "Genesis Countdown" cues from Star Trek: Wrath of Khan.

"Dark Side Beckons" from ROTJ.

"The Fields of Pelennor" from Return of the King, particularly the shot of all nine Nazgul diving upon Minas Tirith.

John Barry's theme for King Kong (1976) is the absolute best thing about that misbegotten film.

Gandalf's arrival at Helm's Deep in "Forth Eorlingas" is, like ANH's "TIE Fighter Attack," one of those musical pieces you can't imagine existing without the corresponding visuals...and vice versa.

All I can think of right now. Back to work.

I love William's Superman: The Movie main title, and the Imperial March.

Poleduris's Anvil of Crom from Conan the Barbarian is epic.

Musical notes in Close Encounter's

Batman - opening theme
Die Hard with a Vengeance - Waltz Of The Bankers
Escape from L.A - Snake's theme
Evil Dead 2 - Attaching the Chainsaw/ Ash crawling out of the cellar
Army of Darkness - Ash riding from the castle/March of the Dead/ Opening theme
The Good, the bad & the Ugly - pretty much the entire score
Hellraiser - Opening titles/Frank comes back from Hell
Hellraiser II - again, pretty much all of it
Jurassic Park - Near the ending when the Rex attacks the Raptors
Matrix Revolutions - Neodammerung

Heh, I've been looking through this thread and Ganner just beat me to it.
In particular, there's a scene in the film that I think is a truly great musical moment.

Where the mute girl is sitting on the floor trying to open up the puzzle box, while Channard and that women (man, I'm great with names today ) are watching through a window. The whole thing runs for about 5 minutes or so and is almost entirely just the music playing while the girl tries to figure out the box and weird things start happening, as this delicate melody soars up into a huge angelic yet evil crescendo as the puzzle box is unlocked and the demons arrive. Just awesome. I don't even like the rest of the film, but this scene with Christopher Young's music is something that's always stayed with me. Just amazing.

I love Conan's music too, in various scenes, but I'll pick out the simple rendition as the recently 'resurrected' Conan practises with his sword on a hilltop.

I'd also like to give a nod to Highlander III's use of 'Bonny Portmore' as Conner, also, tests out his new sword around the hills of Scotland. Wonderful scenery and beautiful, haunting music. Again, like Hellbound, didn't care much for the film but this scene was gold.

And, heh, the music in Shrek where they're fighting the dragon. I don't know, there's just something about the build up and the big soaring finale as they're racing out of the castle that makes me smile

After seeing that new Superman trailer, I totally have to add the opening theme for the planet Krypton to this list. As a teen, this was pretty much the only bit of that score that I really appreciated outside of the main themes, and it's only gotten better with age, IMO.

More favorites:

--John Barry's space launch in You Only Live Twice.
--Danny Elfman's Batman theme.
--Don Davis and Juno Reactor's score for the Burly Brawl scene in The Matrix Reloaded is the most buttkickinest element of a buttkickin' scene of buttkickin' in a movie that frequently only smelled like butt.
--And let's face it. Without John Williams' Carbon Freezing cue, even Ford's inspired "I know" line would've fallen utterly flat along with the rest of the scene. I mean, have you ever seen that shot unscored? I did once at the tender age of 12, and the power of film music was made so clear to me. It's why I'm a film music fan today, over two decades years later.
--The first full statement of the Jaws theme. Who knew two notes -- TWO NOTES -- could be so powerful?

LOTR: Gandalf the Grey rides to Isengard...

ESB: Echo 3 to Echo 7, Han old buddy...

The Passion: Resurection.

Harry Potter PoA: Buckbeak's Flight, the part after they go by the castle, and before they are skimming the water, staccatto horns, with hesitant, starting & re-starting strings.

I love any time in the Back to the Future trilogy when the theme really cranks up.
Especially in the first film at the end when Marty is racing towards the wire, about to be struck by lightning.
So exciting to watch, especially when it all peaks as the Doc glides down the cable from the clock tower to the floor
Great momment.