This site from the Georgia State University provides a good overview of ferromagnetic materials, introducing concepts such as magnetic domains, hysteresis, the curie temperature, and magnetostriction.

This site from the Georgia State University contains a good overview of some of the magnetic properties that are common to all materials, such as susceptibility and permeability, and then specific discussion of both diamagnetic and...

Wikipedia.com offers a good introduction to diamagnetism and diamagnetic materials, including discussion of how superconductors exhibit diamagnetic properties.

This site from the Georgia State University provides a brief introduction to diamagnetism, explaining how Lenz's law accounts for diamagnetic behavior in all materials.

This Wikipedia site is an introduction to paramagnetism and paramagnetic materials.

This site from Wikipedia provides a wonderful in-depth explanation of ferromagnetism, covering the atomic behavior which is responsible for ferromagnetic properties. Also introduces the concepts of magnetic domains and the Curie...

This site from the Georgia State University provides a brief introduction to paramagnetism, explaining how paramagnetic materials exhibit magnetization proportional to an applied magnetic field according to Curie's law.