Molecular Mechanics and Dynamics - Practical tutorial on the topic, including an overview of force field selection and applications. - http://www.chem.swin.edu.au/modules/mod6/
Molecular Mechanics - A tutorial published by the Center for Molecular Modeling of the U.S. National Institutes of Health. - http://cmm.info.nih.gov/modeling/guide_documents/molecular_mechanics_document.html