Robert Schenk, PhD
St. Josephs College: More Price Elasticity
This site explains price elasticity of supply. Includes graphs to represent the concept.
Robert Schenk, PhD
Computing Price Elasticity
This site discusses price elasticity, along with the formula for "arc elasticity," which is a different method to calculate price elasticity.
Khan Academy
Khan Academy: Elasticity in Areas Other Than Price
Elasticity also applies in labor markets and in financial capital markets.