using the sampler info utility in maya (hypershade) allows you to receive information about the shading on a point of a surface; so if you want to create a rim shader in maya connect the facing ratio of a sampler info utility to a the vCoord of a ramp (black to white, smooth) and the the ramp’s outcolor to the ambientColor channel of a material (e.g. blinn). the result is a nice rim shading great for a cartoon-like skin. this way you can also do x-ray effects (by connecting the outcolor to the transparency of the object).
or you just pick up the nice rim shader from autodesk’s area offered by miguel santiago which offers quite a high degree of artistic control without adding any lights to your scene.