IBM WebSphere Application Server Community Edition
http://sourceforge.net/powerbar/websphere/
Learn EJB
http://www.javaskyline.com/learnejb.html
AJAX
http://java.sun.com/developer/technicalArticles/J2EE/AJAX/
Open Source Software in Java
http://java-source.net/
Collected Java Practices
http://www.javapractices.com/index.cjp