I'm not sure what they are exactly, I was hoping to find out through your answers.
Here are some songs that in my mind could reasonably be called 'centrepieces' of their respective albums:
Paranoid Android (only track 2! Thinking out the box)
The Past Is A Grotesque Animal (Hissing Fauna)
All Around The World (Be Here Now)
French Lessons (How To Stop Your Brain... )