You probably aren't a fan of showing up at the coffee shop right when there's a large line, or at the gym when there are no free machines. Wouldn't it be nice if you could find out how busy a place is at any given moment, without resorting to estimates? The new Density sensor might help. The tiny infrared detector is effectively a smarter, more connected pedestrian traffic sensor: it tells apps how many people are entering or leaving a building at any moment, giving you a good sense of whether that restaurant is packed or blissfully empty. Shops can use that data to their advantage, too. They can offer discounts whenever it gets quiet, or notify you the moment there's a free seat.