University of Guelph
University of Guelph: Physics Tutorials: Exponential Growth and Decay
Good site explaining exponential growth and decay, with questions for students to test themselves.
Other
Wpi: Exponential Growth and Decay
This site explains exponential growth and decay and how it applies to the real world with its use in bacterial populations.
University of Saskatchewan (Canada)
University of Saskatchewan: Modelling Natural Growth
This site shows how to model exponential growth. The site walks the student through an example problem using logarithms to find the exponential growth of the theoretical world population.