An article on writing custom Swing components
An article of mine on writing custom Swing components has been published today on java.net. It follows the article on how to write a custom look and feel and the article on enhancing Swing applications with widgets.
Hopefully, these three contain enough information to start you off on the path of writing custom components that play well with both core and third-party look and feels. Note that the latest article focuses mainly on the component building blocks, and less on the "automatization" side (bean interface, playing well with IDEs and builders etc). This is left as an exercise to the reader.
You're more than welcome to comment on the articles.