This thread has gone a little off-topic (as is habitual here), since people are also discussing filmakers' choices for soundtracks rather than strictly filmakers-composers; which is great, as more interesting things are brought forward.
fahl's entry however is completely off the mark, obviously. For interest's sake, 'Prometheus' was a work my wife considered as a topic for her Musicology dissertation a few years ago. She wanted to use Fourier transforms to accurately map the work's sonic spectrum to that of light (no synaesthesia), thus only partly fulfilling Scriabin's vision of gesamkunstwerk - he also wanted particular smells to be aired in the auditorium, etc. - and then perform the work authoritatively for the first time (that is, take the solo piano part) for its 100th anniversary. Sadly, two physics departments said that it is scientifically unsound to claim analogies between sound waves and light waves, and she had to find another topic...
By the way, has anyone really checked fahl's signature? My-my... It sure beats mine.
P.S.: I loved Kubrick's use of Ligeti piano studies in Eyes Wide Shut. One of the best marriages of music to film I have ever known, especially considering the music was not composed for the footage!