[Osiris]

It is sometimes important to concentrate on a task at hand and blend out everything that is not related to it. This could be the case when reading an interesting article, editing a Microsoft Word document or playing a flash game. Everything around the needed area could be a distraction.
Zorro is a great software that runs on all Microsoft Windows operating systems starting with Windows 95 excluding Windows Vista. With Zorro users can blend out parts of the screen that are not relevant to their current task. I can think of several applications other than the ones already mentioned.
It is possible to increase or decrease the size of the window by simply dragging it into the correct position, to select a defined size between 160×120 to 856×480 or make it fit a window. The cursor and the taskbar can be hidden if needed or remain on the screen.

Once you have activated Zorro the rest of the screen will turn black - or to another chosen color. You can turn it back to normal by pressing ESC at anytime.

Zorro can also black out the selection instead of the rest of the screen.I personally would prefer a way to make the rest of the screen transparent instead of filling it with a solid color.
Read More:
Zorro Homepage
via Freeware Genius