Two useful Swing related libraries:
The Swing Application Framework is a light framework that simplifies the creation and maintaining of small- to medium-sized Java desktop applications. The framework consists of a Java class library that supports constructs for things such as the following:
- Remembering state between sessions.
- Easier managing of actions, including
running as background tasks and
specifying blocking behavior.
- Enhanced resource management,
including resource injection for bean
properties.
Here's an article about it. It's been integrated with Netbeans 6.0 and later.
EventBus is a Swing-oriented publisher-subscriber framework that I've found very useful for updating GUIs.