In the INFORMS Fall Annual Conference 2011 at Charlotte, NC, which concluded in November, I did a small presentation on correlated random variables. One of the very important aspect of creating a Monte Carlo simulation model is to consider correlations between the random variables. In this presentation, I talk about why considering correlations is important, how to consider correlations between random variables, and how to generate random numbers from correlated random variables (mostly, using the Crystal Ball implementation as a standard).
Here is a link to the presentation. As always, please comment if you have additional questions.