Eclipse + Tomcat + JBoss + MySQL 3.x
Step-by-step guide by Hao Wu covers setting up the following open source tools for J2EE 1.3 development: Tomcat 4.x for Servlet 2.3 and JSP 1.2, JBoss 3.x for EJB 2.0, JMS 1.1, JCA 1.0, and JAXP 1.1, MySQL 3.x for RDBMS Persistence, Eclipse for Java IDE.

JBoss
Includes source, documentation, downloads, and user forums. [Open Source, LGPL]

Q&A: Behind the Story at JBoss
Marc Fleury explains his vision for JBoss software, which he says will displace commercial Java server software faster than Linux is replacing more entrenched OSs. [ZDNet UK]

JBoss FAQ
Collection of FAQs for JBoss application server.