There are quite a few instances where Levy Distribution is used instead of Gaussian or Cauchy Distribution. What exactly is this distribution? When is it used? When does it fail?
as far as I know Levy distribution is a more general distribution family which includes gaussian, exponential and power law distribution as particular cases. I am not an expert but in the attached links you can find two relevant applications, at least in economics.
You can make a histogram of your observations, and then see how the variability is distributed OR you have a theoretical model of how the variability should be distributed.
The Levy distribution is useful in modelling certain processes whose values are strictly not negative and which can change appreciably over the short term (Levy has a "heavy tail"). Both of these attributes are "non-Gaussian". For example, Levy is frequently used to model stock value in the market: stocks can be worthless, but not negative, and their value might change significantly in the short term. There are also some interesting technical properties, like its relationship to the Gaussian using a transformation.
Here you have, more or less exhaustive answer for your question:
http://arxiv.org/abs/math-ph/0106003
You will also find there a proposed implementation (in FORTRAN), very short, nearly one-liner. In addition, the description of a distribution in question given there is more general than the one given in Wikipedia: