Some time ago I wrote a little script to automate adding rim-lighting ramps to materials. I recently added some defaults so thought I'd share it.
Download and place it in your scripts folder:
PC: My Documents/maya/20xx/scripts
Select a material (Lambert, VrayMtl, Phong etc.), or a texture node (Ramp, File, Checker etc., etc.).
Then in the commands bar or script editor type the following:
python "import AddRimLight"; python "AddRimLight.addRimRamp()";
This will add a ramp and a sampler info node and hook them both up.
Adjust the colours on the ramp to taste, and render away.
Here's a before:
Not bad for the press of a button.
The clever thing we're doing here is adding a sampler info node and using it to power a ramp based on the angle between the camera and the object. The more acute the angle, the more the bottom colours on the ramp will be used.
If you select a material node, the ramp is added to the colour slot (and decent defaults are automagically set for you), if you select a texture node, the ramp is added to the Colour Offset attribute (in the Colour Balance roll down) - defaults are also created for this mode, but they will almost certainly need tweeking.