JSP and Servlet Reference Materials  
   Free PDF of course materials from training courses on JavaServer Pages (JSP) and Java Servlets.
   http://courses.moreservlets.com/Course-Materials/

The Java Home of Kaan  
   The Java Scratchbook and shortcuts : code samples and examples sorted by package names. Java Certification programmer exam questions and answers. JDBC/ODBC connection with MS Access. Terras Game. Topics Deployment Directory Services (Dutch). Quality Pro
   http://home.tiscali.nl/~bmc88/index.html

Java Gotchas  
   Tricky parts to the Java computer language - quirks, features and nasty surprises, and how to get around them.
   http://www.mindprod.com/jgloss/gotchas.html

Java Glossary  
   Roedy Green's glossary of Java-related terms.
   http://mindprod.com/jgloss/jgloss.html

Help4j  
   Repository of code examples from open source projects, tips, links and utility classes organized by Java method and class. Windows and Unix/Linus versions. Integrates with JavaDoc.
   http://www.inventivio.com/help4j.html