Here is a bunch of links to the websites which have a lot of usefull information on Java and related technologies. I have come across these sites over the past 4 years of me working with Java, and I will keep adding them here for all of you.
A list of open-source java based software.
IoC Container Comparison
A great overview of IoC Containers - HiveMind, Spring and PicoContainer
A implementation of Speex Speech Codec in Java. A great tool for building Voice Messaging Solutions.
Windows Tray Icon for Java
Free Java API for getting your app to minimize to a tray icon in Windows.
Dr. James Gosling WebLog
The Father of Java. He's got some interesting things to talk about.
I read this blog a lot. Hani rules. He biles a lot about different Java related issues, technologies and people
My personal blog. This blog will have some tutorials on XTOM before they make it to this site.