University of Colorado
University of Colorado: Ph Et Interactive Simulations: Fourier Making Waves
Learn how to make waves of all different shapes by adding up sines or cosines. Make waves in space and time and measure their wavelengths and periods. See how changing the amplitudes of different harmonics changes the waves. Compare...
Wolfram Research
Wolfram Math World: Fourier Transform Exponential Function
This site explains how the Fourier transform of an exponential function is related to the Lorentzian function. Site also contains relevant links.