The site http://platform.netbeans.org/tutorials/
was updated 5 minutes ago. The Options Window Extension Module Tutorial and the Help System Module Tutorial were both deleted—thanks to Module Development Update 1, which you can get from the Update Center, both of these are now supported in the New File wizard by templates (the Options Panel wizard and the JavaHelp Help Set wizard).
In addition four new tutorials have been added—all of them are by Tim Boudreau, and they all relate to "selection":
So, go to http://platform.netbeans.org/tutorials/, and let Tim guide you further into the world of NetBeans APIs!