You say that it's an 'extra' key, but it's clearly shown replacing the right control key in the layouts HP and Lenovo are using. Moreover, it can't be remapped to actually be right control because it ...

Have you ever been playing a game on your computer and unknowingly pressed one of your Shift keys a few times in a row, only to have your game suddenly interrupted or minimized by a pop-up window and ...

It's really useful outside of games, though. I use it all the time. Press Win, and type the first letters of an app's name to run it; Win+Tab for the improved task view; Win+Number to switch to a ...