I've been working on a light grey look and feel for JavaFX with square corners, inspired by the Swing Substance (Business Grey) Look and Feel. Here are the results so far:
And just as a reminder as to the default JavaFX look and feel:
This is a work in progress and not all of the controls are styled. This skin has now become the first entrant in the jfxtras-styles project hosted on github or click here if you just want to grab source.
The extra space is to show the drop shadows on the titled panes which I use quite a lot in my own application.
Update:
Just to show the different a little CSS styling can do, below is a recent screenshot of EstiMate, the JavaFX project I have been working on. It's come a long way! You can take a look at the CSS here.