Hi Bamdad,
If you have not done so already, I recommend reading David Harel's original article on state charts, which are the basis for FSM. Here's the URL:
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.20.4799
Another good source is anything related to UML state diagrams, such as the following by Scott Ambler:
http://www.agilemodeling.com/artifacts/stateMachineDiagram.htm
If you want to see an example of a complex state machine in action look at the Tungsten Replicator main program. We use FSM to manage network services like the replicator. The code is located at the following URL:
http://tungsten.svn.sourceforge.net/viewvc/tungsten/trunk/replicator/src/java/
com/continuent/tungsten/replicator/management/OpenReplicatorManager.java?
view=markup
Also, if you find bugs or have feature requests. We are not doing much development on this mostly because it does everything we need and has not had a bug report in a long time.
Cheers, Robert