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.
The alternate is obviously the Multi-threaded model. Unfortunately, the Servlet container can't help you in this model as it did in case of Single threaded model. You need to make your application thread safe, by the traditional way - protect the shared resources (if any) yourself.