Picture puzzle software

Does anyone know of a program that will split an image into a grid, then allow you to reveal the image one square at time?

This is the kind of function often used in TV gameshows, where contestants have to guess the image as it's revealed bit by bit.

So far I've only found applications that convert images into mosaics or jigsaw puzzles.

Any help much appreciated.

I'm no Flash expert by a long shot, but I think you could achieve that effect with a Flash animation. I have no idea how to do this specifically, but I think it's entirely doable.