Useful Links

JSP implicit Objects
http://java.sun.com/javaee/5/docs/tutorial/doc/bnahq.html#bnaij
Old version of J2EE link
http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/JSPIntro7.html

Documentation Regarding HttpServletRequest Interface
http://java.sun.com/javaee/5/docs/api/javax/servlet/http/HttpServletRequest.html
Look into the methods of javax.servlet.ServletRequest Interface

Documentation Regarding HttpServletResponse Interface
http://java.sun.com/javaee/5/docs/api/javax/servlet/http/HttpServletResponse.html
Look into the methods of javax.servlet.ServletResponse Interface.

Documentation Regarding HttpSession Object
http://java.sun.com/javaee/5/docs/api/javax/servlet/http/HttpSession.html

Difference Between Web Server and Application Server
http://www.javaworld.com/javaqa/2002-08/01-qa-0823-appvswebserver.html

Good links

http://www.lepus.org.uk/ref/companion/State.xml
http://blogs.sun.com/jkumaran/entry/state_design_pattern_using_java

List of Design Patterns

Below is the URL for quite neat/simple explanation of the design patterns.
javacamp.org

Check out for source code of all the examples and the complete book as pdf at this URL.

Java Design Patterns

Creational Patterns
Abstract Factory
Builder
Factory Method
Prototype
Singleton
Structural Patterns
Adapter
Bridge
Composite
Decorator
Façade
Flyweight
Proxy
Behavioral Patterns
Chain of Responsibility
Command
Interpreter
Iterator
Mediator
Memento
Observer
State
Strategy
Template Method
Visitor

J2EE Design Patterns

Presentation Tier Patterns

Intercepting Filter

Front Controller

Context Object

Application Controller

View Helper

Composite View

Service to Worker

Dispatch View.

Business Tire Patterns

Business Delegate

Service Locator

Session Façade

Application Service

Business Object

Composite Entity

Transfer Object

Transfer Object Assembler

Value List Handler

Integration Tier Patterns

Data Access Object

Service Activator

Domain Store

Web Service Broker

Will be updating EJB Design Patterns below.

For now you can get the complete book of EJB Design pattern, Author Floyd Marinescu from below link

EJB Design Pattern