lambert: has no specular component and can be made into a constant shader by ramping up the ambient colour.

blinn: good for metals and plastics (it's the most commonly used shader). has specular and reflection properties.

Phong: Another variation of the blinn model, but with more components for controlling the specular highlight.

ramps: fade from one (or more) colours into other colours. Can also be used to control attributes such as decay, tranparency etc. (must use greyscale maps for that though)

That should be enough to be getting on with

Alan