This is a Maya shader for faking reflected or bounced light, or creating a rim-lit effect. The variables are tweaked via the ramp node, which is is more or less WYSIWYG. Change the ramp colors to control the color and intensity of the rim-light and ambient color. Move the ramp colors up and down to control the squeeze and amount of light. Use the ramp interpolation to control the falloff. It works with any kind of shader and only augments the ambient color functionality so you can add your own color maps or whatever else you might want.