Wikimedia
Wikipedia: Marginal Utility
This website discusses the concepts of marginal utility and value, with references made to such economic philosophers as Adam Smith, Karl Marx, and David Ricardo.
Council for Economic Education
Econ Ed Link: Utility
Can happiness be measured? Students will learn how utility relates to economic decision making and the law of diminishing marginal utility.
Khan Academy
Khan Academy: Total Utility and Marginal Utility
Practice what you've learned about total utility, marginal utility, and the law of diminishing marginal utility in this four-question exercise.
University of Nebraska Omaha
Ec Ed Web: Analyzing the Demand Curve
Lists the determinants of demand for a product and service. The site is useful for students wishing to look further into the causes of demands. Graphs and summaries are included to aid research.