I use Waze to help give me audio alert when I go over the speed limit. Only thing is that it only alerts you one time and if you go over the speed limit again it will not alert you. I would find it very beneficial but it alerts you every time you go over the speed limit.
   I would also would like to have school zones added and alerted. And possibly have speed limit decrease to 20 mph when school zones are active with audio alerts.
 I live in a very small town and is known to have speed traps. We have at least 7 speed cameras and several speed changes. That go from 55 to 35 to 25 in a short amount of distance apart. 
  An audio alert to hear the speed changes change while you are driving, I know for myself Will help tremendously and alerts to known speed traps towns.