About Temperature - A very basic (prepared for the middle school math teachers) tutorial but still useful for professionals.
All Thermodynamics - from HyperPhysics portal. This is rather a comprehensive online physics handbook containing "Thermodynamics" chapter. Site has a handle navigation, good illustrations, and very detail content.
Applied Thermodynamics - Definition and short explanations of terms, units and basic principles.
Basic Terms and Theory - from Engineers Edge. A definitions, short explanations and connection of basic thermodynamics terms.
Carnot cycle - Applet showing the physics processes of a Carnot heat engine by Fu-Kwun Hwang of the National Taïwan Normal University.
A Concise History of Thermodynamics - An overview of the history/evolution of thermodynamics. This is an excerpt from a biography of J. Willard Gibbs. The overview is available from the site in MS Word or pdf/Acrobat format.
The Expert System For Thermodynamics - TEST is a visual environment to solve thermodynamics problems, pursue what-if scenarios and perform numerical experiments.
Ideal Gas Law - Applet illustrating the ideal gas law : action of a piston in a pressure chamber filled with ideal gas.
Internal Combustion Engines Web Site - Thermodynamics and heat transfer in Internal combustion engine. Applets are used to perform simple calculations. Developed at Colorado State University.
The Second Law of Thermodynamics - A qualitative introduction to the second law and entropy written for beginners in chemistry but useful for physics students too. Explains relationship with Murphy's Law.
Thermo Fluids Engineering - web page of the division of the Eindhoven University of Technology which study processes where fluid flows and heat transfer play a prominent role.
Thermodynamic Toys - Contains directions for making toys with thermodynamics background.
Thermodynamics and Its Applications - Companion site to the textbook by J. W. Tester and M. Modell, includes answers to selected problems and current errata.