I forgot to add that we have pedometers and HR monitors, but most students opt to use their smart phones with GPS to track movement and pace/speed on a run. They enjoy checking their progress.
We use heart rate monitors with our classes. It is a great way to track students effort level when working on cardiovascular training. Although some students may "look" like they are doing very little, with the HRM their heart is working extremely hard. HR Moniotrs can make class much safer for those student who are not in very good shape.
I use my ipad all the time. It helps me keep track of my students by taking attendance. I use it to take photos of students in action. I can access web material and use it to display content with my projector.