Most people know about the "Dark Side of Oz", where you watch the Wizard of Oz and listen to Dark Side of the Moon by Pink Floyd. Of course, it never works, it's silly, and all that. However, there's another such combination that does work. The end of 2001: A Space Odyssey is a chapter called "Jupiter and Beyond the Infinite". It's relatively the same length as the Pink Floyd song Echoes off the Meddle album (23 minutes). Start the song when the Title screen for the last chapter first shows up, and it should sync rather well. Or you can find pre-mixed copies of it on YouTube somewhere.

There's actually a probable reason behind this, which is that it was most likely going to be the theme music for that chapter. It's a well known bit of trivia that Stanley Kubrick didn't want all that classical music for the themes of his movie adaptation, but they were low on money and it was all Public Domain.