Sensors & Detectors

Im going to record the sensors and detectors and programs that i go through or witness day-to-day that benefit me and/or others, some examples;

 i drive around a lot and noticed that my car has a reversing sensor that beeps when the car is reversing too close to another car or object. another sensor i found while driving, (and the one i dislike most) are speed cameras, good for road saftey...but for the days you feel a bit too brave and feel like hitting the gas and then get flashed (not a good feeling when you get flashed), camera takes your registration number and through that they find the address the car is registered to and then you get your ticket..abit like barcodes, you scan it and find a whole load of information.
you can get barcode detectors as a app now...phones have sensors too, touch screen? accelometer?