• Sytrus has a multi-segment line generator, but each line is one of some number of curves.
• It looks like most of the standard curved ramps can be created with a cheap quadratic bezier curve.

Links

• Wikipedia

Obligatory but not the easiest read.

• Animated Bezier Curves

A site where you can visually play with curves.

• Quadratic and Cubic Bezier Curves

Another explanation site; not a lot of details.