MonkeyWorld3D is a scenegraph editor for the jMonkeyEngine (jME). You can edit scene elements, terrain, physics and animations. Our aim is to make a WYSIWYP (What you see is what you play) game editor.
The Deimos Project is a Java-based game development library collection. Includes Vertex Modeler, a 3D modeler that lets you programatically define models using Java source code. The modeler is also a simple scenegraph API.