How many tiny accelerometers do you depend on? There’s the one in your smartphone, telling it which way’s up, so it can adjust the screen horizontally or vertically (or track your footsteps or how fast you’re running, or for that matter, transform your iPhone into a seismometer).
For similar reasons, there’s one in your FitBit-type contraption too. Then there are devices like Microsoft’s Kinect and Nintendo’s Wii which use them to help track motion. And that’s not all. You can find them in toy remote control cars (and real cars, which use them to detect rapid deceleration and trigger your airbag) and even medical devices – where they might soon help control when and how much medicine you get.