The movie Jaws is on TV right now. Even if it hadn't been a terrifying and nearly perfect film, it would have been remembered for the awesome score - an Academy Award-winning effort; Best Music, Original Score (1976). So let's make it's theme the Song of the Day!
Sometimes it's hard to tell which was better: Robert Shaw as Quint, the shark hunter, or John Williams's score. Everyone knows it and it's a great conversation starter. The theme is also used to enhance any conversation as it sets the mood whenever anyone starts in with "Daa dum ... Daa dum ... Daa dum ..." though usually to comic effect.
That's the problem with popularity. With popularity comes familiarity and that, as the old saw tells us, breeds contempt. Unless taken in context with the film, the theme doesn't elicit chills any more. Mr. Williams has a number of film scores that this can be said about: Star Wars, Jurassic Park, and E.T., to name a few.
I've heard of a few DVDs that allow the viewer to watch the movie, or at least some parts of it, without the score to judge for themselves how important the music is to the overall project. Most people don't give it a second thought if they even notice when the composer uses hints of a theme to alter the mood, set an expectation, or even fool the viewer. Mr. Williams is a master at this. Combine this talent with a haunting melody as in Jaws, and an instant classic is born.