Wolfram Research
Wolfram Math World: Natural Logarithm
This site gives graphs of logarithmic functions and pays particular attention to base 10 and base e (natural logarithm). The site explains how to change bases, the importance of the natural logarithm in calculus, incorporating the...
University of Saskatchewan (Canada)
University of Saskatchewan: Exponents and Exponential Functions
This site reviews the basic properties of exponents, and explains rational exponents and exponential functions, including those with base "e." Provides examples and lots of exercises.