I was trying to use jMonkeyEngine for a 3D engine with NyArtoolkit these few days. I uploaded my first result on Youtube.
jMonkeyEngine is a 3D game engine written in Java. It supports many features such as collisions, particle systems, shaders, terrain system and so on.
Here, I put my source codes however I modified original NyARToolkit utils library for a compatibility between mac and windows so they might not work. If you have any question, feel free to ask.