Read this article referenced in Dhar's blog. One of the things that author suggests he has learnt from playing FPS is to face towards entrance when sitting in your cubicle. I have seen better solutions to boss catching you surfing net or watching educational stuff. The answer is rear view mirror. I have seen a couple of them in the office here (they seem to be very common), more over they are portable, you can carry them with you when you change jobs, some of them use velcro to stick to your monitor top left/right corner. Will try to post a photograph sometime.