Apple's most recent Pro Tip teaches us how to move the Dock with a simple click and drag (here's the abbreviated version: shift click on the Dock dividing line and then drag the Dock to the left, right, or back to the bottom of the screen). I'm not sure how that qualifies as a Pro Tip, but I am sure it is news to some people.
It did get me thinking about where people keep their Docks. I'm a traditionalist myself, I never feel at home unless the Dock is at the bottom of my Mac's main display. Where do keep your Dock? Let us know in the comments.