You can read about mod_perl at perl.apache.org and about Mason at www.masonhq.com.
You can read more about J2EE at java.sun.com. The Apache Software Foundation's Jakarta Project, for open-source Java software, is at jakarta.apache.org.
The main Zope page is www.zope.org. A good site for those new to Zope is www.zopenewbies.net, and a site for more sophisticated users is at www.zopezen.org.
Finally, the OpenACS community is available at www.openacs.org. The PostgreSQL database, which you can use with OpenACS, is available at www.postgresql.org.