Here's a text-based tutorial that I created to help you spice up your scenes with textured lighting. We’ll take a look at how simple it is to drastically effect the look and feel of your renders by applying textures to lighting. Applying a texture to a light is generally the same as applying a texture to an object. The only difference is that we’ll be projecting the texture into the scene based on the light settings.
Although not a lighting tutorial that goes into great details of the lighting setups, we will take a look at the basic function of the lights within the different scenes. We’ll also cover how to create your own simple textures for the lighting. The last example will show how simple it is to use a video as a light texture.
These techniques will allow you to create interesting light and shadow patterns that can help frame the "story" and context of your scene; thus helping you to create scenes that no longer appear to exist within the all too common CG vacuum. They will also allow you to add subtle variations to your lighting instead of the ultra-clean lighting often seen when using very basic lighting techniques.
This tutorial requires a knowledge of the basics of applying a texture to an object in Blender.You can view the tutorial at BlenderCookie.com.