The Virtual Laboratory (G. Bothun), University of Oregon, Eugene, OR.

http://jersey.uoregon.edu/vlab/
Thermodynamics/index.html

This lesson looks at the time it takes for a system to come into thermodynamic equilibrium and observes the diffusion process.

http://www.stirlingengine.com

from the American Stirling Company.

This site is for the American Stirling Engine Company, and has lots of information about different Stirling engines and several animations which the company produces. Here are two other links to Stirling Engines Sites: The English Stirling Engine Page by Koichi Hirata and Stirling Motor! by Ralf Moros. Both are very good, but Stirling Motor! is in German and so the activities are not available in English.