If you press Ctrl+Alt+Left Arrow, the screen will rotate sideways.
Why would you ever do this? Maybe you have a desktop and you’ve turned your monitor into the portrait direction. Or maybe you’ve got a laptop and you’ve placed it on its side.
Regardless, to get back to the normal direction, press Ctrl+Alt+Up Arrow.
This one is in the category of “good prank to play on someone on April 1st.”
Sometimes you want to minimize every window except the one that you’re using, so that you can see the desktop but keep working.
Press Windows and the Home key. All other windows minimize down to the task bar.
Press Windows+Home again, and the other windows are restored to where they were.
Note that if your active window is maximized, you won’t really see anything happening. This tip is only useful if the active window takes up less than the full screen.