Instructable’s user Dimovi has done an awesome LCD monitor hack to create the ultimate privacy display. Everyone can do this. Really, the tutorial is dead simple and what you want to do is to take out the polarized film from the monitor.
this way you will see only a blank display, but if you use the polarized film outside the images are crisp clear. You will need o create some special glasses by cutting that film and adding it to the glasses. This way only you can see what that monitor show. This is freaking great. Thanks [OctiZip].