Two come to mind without hesitation:

OHMSS: "We have all the time in the world" sung by Louis Armstrong whilst Bond romances Tracy (montage sequence) before getting back to the spying business. Oh, so appropriate. (okay perhaps it is not the full OST/single release version but it's close enough);
The Dove: "Sail the summer winds" sung by Lyn Paul as we see Robin Lee Graham sailing his boat Dove with wonderful photography (I think it is a short montage).

Both scored by John Barry - strange that?

Mitch, September 17, 2004; 12:04 PM

QUE SERA, SERA, performed by Doris Day in Hitchcock's remake of his own THE MAN WHO KNEW TOO MUCH. That was the first one which came to my mind.....It's a brilliant use of a wonderful song in a suspenseful situation: Doris is performing the song which she and her son in the film both love, and as she's singing this during a party in a house....in which her imprisoned son is upstairs awaiting the arrival of the villains who will kill him....the sympathetic villain woman encourages the boy to whistle the tune as loud as he can. Doris hears it downstairs, as does James Stewart, and Stewart is able to find the boy and rescue him.

Great sequence and great, best-ever use of a song!

kriegerg69, September 17, 2004; 7:43 PM

Since Mitch already mentioned We Have All The Time In The World (probably the best 007 song), and since we excluded all the title/credits songs, I can add my favorite

"Le Gâteau Empoisonné" from ASTÉRIX ET CLÉOPÂTRE (1968)

by Gérard Calvi. Though the other songs in this great movie are also great.

42zaphod, September 17, 2004; 9:47 PM

"The First Time Ever I Saw Your Face" by Roberta Flack from "Play Misty For Me". It matches the mood of the film perfectly at the point at which it is played. I believe the entire song is played as well.

df789, September 18, 2004; 9:27 AM

Comes to mind "Have Yourself A Merry Little Christmas" (Frank Sinatra) used during execution scene in the film "The Victors"
Beautiful black/white landscapes covered with snow. At first the viewer is wondering whats up then it becomes clear soldiers are arriving as witnesses to an execution for desertion.

The entire film is one of the best "anti-war" documents ever filmed! Produced by a crew of professional who knew well the subject described.

Also comes to mind is a piece of Italian insanity "Dracula Cha Cha Cha". Don't ask me what film it's from for I have not the slightest idea.

Cha Cha Cha!

, September 18, 2004; 10:08 PM