Cinemadrape!

LeDimmer is a small Windows application (<200KB) that sits in the system tray and simply dims the screen around the foreground window.

TunnelVision allows you to hide the parts of the screen where your mouse cursor is not, effectively increasing privacy (though at a cost).

Zorro is a utility to completely blank the screen except for a rectangular area selected by the user. This is especially useful for watching videos on your computer without being distracted by other programs.

A program that darkens the whole Screen, except an user-defined area (which may include a video) for keeping the contrast if the background is too bright. It also works with several Screens.