ImageWatcher
Requirements:
Windows 2000/XP/Vista
.NET framework
Download and run the installer.
Once installed (you will also need the .NET runtime framework - it's likely you already have this installed, but if not it can be downloaded direct from Microsoft), run the program from Start -> Programs -> IkonTools -> ImageWatcher.
Then simply enter or browse to the path of the folder you wish to watch for incoming images, select if you want to see the image filename and a histogram, and click "Go". ImageWatcher will then go full-screen (initially black) until an image file is written to the folder you specified. Once the image is written, ImageWatcher will load it and display it full-screen with the options you selected. As soon as another image is written, that will be displayed, and so on.
To exit the full-screen mode, simply hit the Esc key.
Simple, easy to use, and rather useful!
Requires the .NET framework runtime from Microsoft