Internet of Blood, Sweat & Tears
I have amassed close to four years worth of running data using various Nike+ devices. It started with the Nike+ Sportband pedometer (since repleced with NikeFule band). That captured pace, distance, time, calories burned, and -- if I was wearing a heart monitor sensor from Polar -- heart rate. Then I bought the Nike+ Sportwatch with built-in GPS. So for the last year or so, all my runs are mapped, including elevation, lat/lon, satellite view/map view, etc. In each diary entry you can make comments about the run; indicate street, trail, track, treadmill or beach; choose from five weather conditions, and a five-grade scale on how you felt.
After four years this adds up to a tremendous amount of data just for me, and Nike is storing it all for free. As of August 2013, more than 18 million people were using Nike+ to track fitness. Now that's big data!