'p' for settings 'r' to reset space to clear the screen
Nebula Generator is simply Curtain, but in 3D space. It's drawn over and over semi-transparently, and eventually the forces combined with the constraints allows it to create a very organic nebula-like piece of art.
At the moment, the "Try Demo" button isn't working quite right. So while we wait for Hawkee to fix it, you can try out the applet online here: http://bluethen.com/wordpress/index.php/processing-apps/nebula-generator/