I’m considering buying a 3-D mouse such as a 3Dconnexion SpaceNavigator or SpaceMouse to use in a JME3 game. I found this video of a student project which used a SpaceNavigator (and a data glove) with JME:
I use it every day at work (I integrated it into our CAD program). Integration wasn’t that bad, albeit using the native libs in C++ (there doesn’t exist a java port, that’s officially supported at least), but a few JNI methods and you are good to go. 3D mice are very fun to use (can take a while to get used to tho), but for object mode, and fly through camera setups they are very sweet!! As inputs you get RX RY RZ and TX TY TZ as different intensities, and also any button presses if the mouse has any.