Visual Library is a library in NetBeans, which you can use in standalone Java apps, for doing beautiful, complex, animated layouts. JUNG is a library for exploring graphs of connected data. What if we put those two things together? That's what I did. The result is on GitHub.
How to use JDK 7's AutoCloseable for more than just I/O.
A while back I wrote support for Outlook-style completion tooltips for JLists and JTrees for NetBeans' Explorer components - for cases where part of a tree cell is not visible in a JTree or JList without scrolling. It's not NB specific - you can use it in your own apps as well.
Interested in API Design? Or in the Lookup API in NetBeans? Writing regression tests for deadlocks and memory leaks? We're doing talks on these at JavaONE...please come join us. And this Monday at NetBeans Day (free!) I'll be spending two hours teaching plugin development and NetBeans RCP.
I wrote a prototype replacement for the Wizards API in NetBeans - trying very hard to create something clean and easy to use, especially one which didn't require the user of the API to write any more code than really necessary. It's now a project on java.net and I'd love to get some feedback.
There are now weekly source snapshots of J2SE 6.0 (Mustang) on mustang.dev.java.net; but many people want to just try making some change in Swing, not building a whole JDK. In this post, Bino George of the Swing team tells how to build Swing in NetBeans - so all you do to build it is press F11, and all you do to run SwingSet is press F6.