Wolfram Research
Wolfram Math World: Hyperbola
This site contains a vast amount of information relating to the hyperbola, including the definition of a hyperbola, equations in various systems, including polar, and many important characteristics of hyperbolas. Site also provides many...
Discovery Education
Discovery Education: Web Math: Graphing Hyperbolas
WebMath offers a java applet that allows you to input information about hyperbolas in one of eight forms and gives you the graph of the hyperbola.
Purple Math
Purplemath: Completing the Square: Ellipses Equations
Demonstrates step-by-step how to complete the square for ellipses and hyperbolas. Includes several charts and graphs for understanding.