Sidebar
"Windows has always allowed its taskbar to be dragged to any edge of the screen, but I've never seen anyone move it from the bottom edge - so it's a solution looking for a problem."
I use it that way right now. Granted, I just started within the last few months, but I was getting sick of having no veritcal resolution. It only makes sense with todays wider and wider screen displays.
That being said, I used of WindowMaker and Afterstep (set up with one column of buttons along one side of the monitor) for quite awhile. I see to remember running a command to move the Apple dock to the left side of the screen on my housemate's Mac some years ago too.