Java Developer Connection - Sample Code
- Large list of code samples.
- http://java.sun.com/developer/codesamples/

Open Source Projects at JavaKB
- An extensive directory of Java open source projects.
- http://www.javakb.com/Uwe/DirCat.aspx/Dir/Software

Manageability - Java Open Source Lists
- A Collection of Collections of interesting Open Source projects written in Java.
- http://www.manageability.org/blog/opensource/view

Java Source Codes @ VyomWorld.com
- Categorized Java source codes from beginners to advanced level topics.
- http://www.vyomworld.com/source/LanguageHome.asp?LangId=5

PLEAC-Java
- A reference to solve common programming problems using Java. [Open Source]
- http://pleac.sourceforge.net/pleac_java/

cgi-bin.com: Java
- Provides annotated, user-reviewed links to a wide variety of free and commercial Java applets, servlets, and JSP.
- http://www.cgi-bin.com/Java/

CodeArchive - Java
- Archive Java applets, applications with sources.
- http://www.codearchive.com/dir.php?go=0400

Servlet and Java ServerPages Source Code Archive
- Source code archive from Sun Microsystems Press book, "Core Servlets and Java ServerPages". All code free for unrestricted use.
- http://archive.coreservlets.com/

Freshmeat.net Java projects
- Browse all Freshmeat.net Java projects (mostly free software) and filter them by various categories.
- http://freshmeat.net/browse/198/?topic_id=198

Free Software Foundation Java Pages
- A collection of Java programs and projects that are licensed with the Gnu Public License (GPL). [Open Source]
- http://www.gnu.org/software/java/java.html