We spent quite a while in Chapter 9, Gamepads in Greenfoot, covering Gamepads and how they can enhance user experience. There are other, very interesting devices you can connect to your Greenfoot scenarios as well. For example, you could connect a Leap Motion or Microsoft Kinect device to provide a very unique and compelling form of user interaction. Also, you can use Greenfoot to control devices such as the Finch robot.
This provides a whole new avenue for you to exercise your creative skills. The following are the resources you can consult to learn more about connecting these devices:
For Leap Motion, refer to https://developer.leapmotion.com/getting-started
For Microsoft Kinect, refer to http://www.greenfoot.org/doc/kinect
For Finch Robot, refer to http://www.greenfoot.org/doc/finch