99% of web apps involve a database

mission critical web applications likely to be clustered.

Simple web applications with JSPs/Servlets upgrade to jboss As with tomcat embedded.

Intermediate web applications with JSPs/Servlets using a web framework such as Struts, Java Server Faces, Cocoon, Tapestry, Spring, Expresso, Avalon, Turbine.

Complex web apps with JSPs/Servlets, SEAM, Enterprise Java Beans (EJB), Java Messaging (JMS), caching etc.

Cross application middleware (JMS, Corba, JMX etc).