Here you will find information about the evaluation of financial options and the theory, definitions and models behind.
This webpage provides Java Applets to calculate the price of complex financial options, using the Monte Carlo technique, Binary Trees, among others.
The source code written in Java and C++, together with information about the structure of classes is available. The programs have been written following the Object Oriented Paradigms.
Check this table, with option pricing applets.
Check it out Java code for Bates Model analytic pricer for Vanillas (good for calibration)