@Raoof, as @Maxim alredy gave You, some, I will continue in that sense, links follow:

http://www.softpedia.com/get/Others/Home-Education/Monte-Carlo-PCA-for-Parallel-Analysis.shtml

http://download.cnet.com/Monte-Carlo-PCA-for-Parallel-Analysis/3000-2053_4-75332256.html

http://www.ohio.edu/people/brooksg/software.htm

I have experience in both Monte Carlo simulation and hydrologic modeling. My Monte Carlo work was related to remediation design, while my hydrologic modeling is with the Hydrological Simulation Program in Fortran (HSPF). I have designed an open source Python Package to run HSPF, PyHSPF, that can be run in parallel for Monte Carlo (although I have not really done this).

https://github.com/drduffman/PyHSPF

http://people.revoledu.com/kardi/tutorial/index.html

This is not a tool but I have found it a great source to start with, especially if you are unfamiliar with the topic.

YASAIw is another free Excel add-in for Monte Carlo with open source VBA. The open source VBA allows you to functions if you need to. YASAIw is capable of calling other VBA programs for each iteration of the simulation (for example if your model is written in VBA or if you write a VBA subroutine to call an executable program that runs your model). YASAIw is available at this link:

http://www.ecy.wa.gov/programs/eap/models.html

For a resource on learning MC simulation, try looking at:

http://www.vosesoftware.com/ModelRiskHelp/

It is free, online, searchable version of our ModelRisk help file and has > 1000 topics.