This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Servlet chaining may be used in scenarios where each Servlet processes the request in a unique way and passes it on to the next for additional processing. Nowadays, Filters are used to do this kind of activity.