Esus - FAQ-like collection of answered and unanswered questions, with categorized collection of links. - http://www.esus.com/
JavaCommerce - Collection of tutorials, FAQs, and articles. - http://www.javacommerce.com/
JavaFAQ.nu - Publishes tips on the site and in newsletter (twice a week). - http://javafaq.nu/
Java Coffee Break - A free guide to the world of Java programming, packed full of free articles, tutorials, book reviews, and FAQs. - http://www.javacoffeebreak.com/
Starting Java Development - Installation and setup help articles, like PATH and CLASSPATH issues. - http://homepage.eircom.net/~pugsleypaul/java/jstart.htm
SwingWiki - Collection of tips, tricks and howtos for J2SE Swing programming. - http://www.swingwiki.org/