Fearofphysics.com: How to make a Roller Coaster Work
Choose from three tracks to see which one would make the best roller coasters, and then watch an animation of your choice.
MyPhysicsLab: Roller Coaster
Use a Java applet to see how a roller coaster would behave on a variety of shaped tracks.
Physics of Roller Coasters
Learn about the history of roller coasters, g-forces, and banking.
Roller Coaster Physics
A short introduction to the physics of roller coasters. Includes conservation of energy, friction, and centripetal acceleration.
Contains historical photographs, biographies, and an animated film which features an interactive virtual tour that explains the physics of motion.
Wikipedia: Roller Coaster
Encyclopedia article contains a description of what it means to be a roller coaster and a short section on coaster mechanics.