Here is a listing of other sites that have been recommended to us.
General Java
Oracle Java Site used to be known as java.sun.com - the obvious one, really!
Learn Java Features original articles, free Java source code, Java programming contests, chat, forums, tutorials, free mock exams for SCJP, SCJD, and SCWCD certifications, and tons of categorized links. (The site is currently stagnant, and looking for a new leader.)
JavaWorld
Methodologies
Scrum Methodology This site contains all sorts of resources for one of the current (2008) Agile methodologies.
Community
Artima.com - a Community of Object-Oriented Developers
TheServerSide.com - the enterprise Java community
javapractices.com - Concise presentations of java programming practices, tasks, and conventions, amply illustrated with syntax highlighted code examples.
vogella.de - Tutorials around Android, Java, Eclipse, web development and other topics.