I'm always surprised when I see someone is using the dock on the bottom. Putting it on the sides is much more efficient -- it takes less effort to move the cursor sideways than it is to move it up and down. I find having the dock on bottom puts more strain on my wrist over a day of working. Another benefit of having the dock on the side is that it's a more efficient use of space on widescreen monitors. Vertical document space is at a premium on widescreens, so why make that worse by putting a big dock down there?
You can even force the Dock to the top if you really want to. Although the Dock and the top Menu start tripping over each other.