adam bien's blog
                    Top Eight, Non Java, Netbeans 6.5 Features 📎
         - CSS editor: with syntax highlighting, code completion and preview.
- HTML editor with auto completion, syntax highlighting, basic drag and drop
 
- CVS, Subversion, Mercurial integration: I use it e.g. to synchronize the chapters of my current book with oreilly.
 
- JavaScript editor / debug support
- Favorites: The ability to browse the file system and edit files. NB can be used as a generic editor.
- Services: Great database viewer with paging, inline editing etc.
- UML support (additional 7MB plugin): really good tool for creating overview diagrams etc. I used it to illustrating my recent books and articles. I saved a lot of time :-).
- Java FX support (additional plugin): compiling, debugging, auto completion, draggable applets, web start etc.
- Diff functionality: you can diff any files you like. [I forgot this point in the origin post :-)].
 
...and Groovy, Grails, PHP, Scala, Python support - I do not use them, however, in my current projects.