I recently came across a video of The Wizard of Oz with Pink Floyd’s Dark Side of the Moon as the soundtrack on Google Video. I first heard about this back in the late 90’s (’98?). Funny how these things come back around again. The best sequence is the 8 minute mark to the 20 minute mark.

8:07 The wicked witch arrives at the exact same time that the bells go off.

14:45 The music turns ominous when the sky darkens and the winds begin to pick up.

16:00 Intense female vocals start when Dorothy starts to run around, avoiding objects that have been picked up by the strong winds.

17:15 The music starts to die down and the vocals become calmer when Dorothy gets knocked out by the blown in window.

18:29 The female vocals intensify again when Dorothy sees the witch on her bike.

19:31 The sounds of the cash register start after Dorothy opens the door and the movie switches from black & white to color.

This site has a more complete list of things to look for.