Are you worried about someone looking over your shoulder, reading what is on your screen?
I may have found you the answer.
With the help of some recycled 3D glasses from your local multiplex, some polarising filters, a tube of glue and a sharp knife, you could make it impossible for anyone to read what is on your LCD monitor's screen *unless* they are wearing the right eye furniture.
Check out what you can do by watching the following video:
Yes, anyone who is not wearing the glasses won't have a clue what you're looking at - all they will see is a blank screen.
Neat, eh? Okay, so it's perhaps not entirely practical for most of us - but if you have some old hardware lying around it might make a fun weekend project.
A full guide on how to make your own privacy monitor can be found on the Instructables website.