Favorite soundtrack moments?

Can you think of a time during a movie when the song or score being
played just fits the scene perfectly, or adds another dimension of
meaning even?

My favorite has to be during Trainspotting when Perfect Day by Lou
Reed is used in the soundtrack. Not only does it fit beautifully, it
was obviously carefully chosen for the movie and scene in particular.

At first listen, you might think Perfect Day is love song, and even if
were a love song, it would still be beautiful in the movie. However,
the song is secretly about heroine, which is a bit of trivia some
people who see the movie may know and some may not. The fact that they
used a love song that wasn't REALLY a love song, that was actually
about HEROINE in a movie about HEROINE almost made my mind explode.

Anyways, enough of that. What are your favorite movie soundtrack
moments? Hmmmmm?