The University of Washington is developing wireless devices that can operate without a battery. The devices operate by reflecting radio waves in the air. Although I can think of many uses for these devices, the article points out one in particular.
For example, sensors placed in a bridge could monitor the health of the concrete and steel, then send an alert if one of the sensors picks up a hairline crack.
After reading that, I was struck at the amount of data that could collected. Just think of all the bridges in your city/state/country. All this data is going to need analysis. Which alerts require immediate action? This sounds like a bigdata problem to me.
How can you imagine these devices being used?