This SST (Stupid Shader Trick) isn't for the materials room. It's used with spot lights. 

There are many additional functions in the Spotlight > Effects tab but I'll concentrate on the ones that are shader based: Gel and Gradient. 

Gradient Shaders in will allow you to change color and intensity of a single spot light across the area it lights. It's a super easy way to add visual richness, suggest additional environmental light yet retain consistency of using a single spot. 

I've uploaded a portrait and an exterior scene to demonstrate.

Gel Texuture Maps are a super way to project effects onto your objects in the scene. (I used a blurry/splotchy gel in my Mayan scene in 'Tis for the Glory 11 to fake shadows from vegetation) In the sample I've uploaded here, I'm projecting a computer display onto the characters face to better tell a story of what is around him. 

Faking water caustics can be done really easily with a gel also – even animated if you have video.