“The Next to Last Song” from Dancer in the Dark.
No votes for the numbers from “The Adventures of Priscilla Queen of the Desert”? I’m shocked!
Dragonblink the Drag King
I’m new here so I hope I’m not infringing or breaking the etiquitte of the boards but I noticed there was not one mention of one of my favorites
Grease
“Summer Lovin’”
“Sandra Dee”
“Greased Lightnin’”
I know they weren’t Fred and Ginger but there was certainly some chemistry between John Travolta and Oliva Newtom John!
Other musicals with big production numbers that are favs of mine:
Anchors Aweigh
Singin’ In The Rain
Wizard of Oz
The Sound of Music
Mary Poppins
White Christmas
just to name a few 
“Springtime for Hitler” from The Producers.
“The Rabbit of Seville” from The Rabbit of Seville.
(Always Look on) The Bright Side of Life from Monty Python’s Life of Brian.
For the sake of my almost three year old I have to second Donald O’Connor’s “Make Em Laugh” number from Singing in the Rain. He (my three year old) dances to it and does pratfalls…
I prefer the “Moses Supposes” number from the same film.
Temple and Robinson in “The Little Colonel” for the cuteness factor.
And no one’s mentioned Hair?
Now, the play has aged dreadfully (to the point that I’m deeply suspicious of whether it was ever any good), but the Milos Formann film is really a gem. A few highlights:
Aquarius
Black Boys/White Boys (with Nell Carter!)
The Flesh Failures/Let The Sunshine In
The Flesh Failures opens with this brilliant shot of a long line of soldiers bording a transport bound for Vietnam. Deeply affecting.
And I’d argue Yellow Submarine merits a mention, especially for the unbelievably gorgeous Lucy in the Sky with Diamonds sequence - if you haven’t seen the newly-restored version released last year, rent it!
Oh, and the entire Umbrellas of Cherbourg, with the most radiantly beautiful Catherine Deneuve.
Another 70’s musical that has not aged well…“GodSpell.”
But it does have some great songs.
“Day By Day”
“Prepare Ye The Way”