It would be great if there were JUCE classes for accessing sensors. They open up so many possibilities for creating innovative and responsive musical instruments or effects and are essential for many games.
Most mobile devices have accelerometers, gyroscopes, proximity sensors, location sensors, compasses, barometers, temperature sensors, etc. And if we go beyond mobile devices and look at the Raspberry Pi, for example, we find ultrasonic, infrared, capacitive, magnetic sensors, radio recievers, etc. I am sure very interesting things could be done with them.
But setup can be tricky and very tedious, so JUCE classes which gave easy and consistent access to at least the most important of these sensors (and ideally most of them) would be a great addition.