Sounds like Lamp textures. Or possibly just textures directly on the object. I'll just talk about lamp textures here.
Just like any mesh you can add textures to a lamp. So, if you wanted the lamp to project an image, you would add a Image or Movie texture to the lamp and when you shine the lamp or spotlight on an object it would use the image/movie as the light rather than solid color.
You can also make lamps work on certain layers in Blender. So, as an example, let's say you only want a lamp to light up Cube1 and not Cube2. You would move the lamp and Cube1 to their own layer and put Cube2 on a different layer. Then in the lamp settings, where you can choose which type of lamp you want to use, you check the This Layer Only box. That way, the lamp will only light up the objects that are on the same layer as the lamp, which would be Cube1.
Then, you could animate the lamp to move and point at what you like. Depending on how you texture the lamp light, you may not even have to animate the lamp at all.
Does that help? I think I was a little vague in some spots, so let me know if you would like a little more detail somewhere.