efunda: engineering fundamentals

I found this great website today, and used a couple of their java-script plotters to explain parametric equations. 

efunda stands for engineering fundamentals. 

Here is an excerpt from their website:

eFunda stands for engineering Fundamentals. Its mission is to create an online destination for the engineering community, where working professionals can quickly find concise and reliable information to meet the majority of their daily reference needs.
eFunda is all about the basics, for most part, that means college level material covered in engineering schools. If you practice engineering, more often than not you would find yourself searching for something you knew but could not quite remember. eFunda wants to be your reminder of these formulas. Not only that, eFunda wants to tell you exactly under what conditions those formulas apply, so you don't have to read an entire chapter of the good old textbook.

http://www.efunda.com/about/about.cfm

This is the java applet I was playing with.