Transparency along a curve || individual transparency

Hi @ all,

I want to add a transparency which is following the shape of the curve.

Example #1: A curve similar to an 'S' which should represent a snake. The back shall have a slight colour shift. For this I though of using the transparency tool.
Example #2: Bold letters shall have a transparency following theire form. So that they look kind of 3D

How can I generate this? Anyone an idea?

(A curve with a colour changing contour and 250 stepsis giving the effect but not helping due to the stuff on top of the curve)