UI Intuition

My mind loves to ponder UI, and ways to expose functionality without cluttering it up.

Today when I was using Google Chrome, I asked myself, how can I get a list of sites I've been to since there isn't a drop-down button beside the back button? I thought, wouldn't it be clever if the user held down the mouse button while clicking the back button, the list would appear?

I tried it and it happened. Then I smiled :)