The windows key is pretty handy. Lots of good shortcuts, and they add new useful ones often. I don't tend to hit it by itself much anymore, because the start menu is so terrible and inconsistent, and anyway, we only run three programs anymore.

I don't think I've used the menu key... If I want to right click, there's the mouse, or mousekeys... But maybe I just missed out on learning to use it. Mostly everything in the context menu is in other places too that you might get to with the keyboard.