I've been using a Android app called JBV1 (John Boy's app for Valentine One) although it does not require a Valentine One for most of its features.
I started using it just go get better false alert filtering for my radar detector but I'm absolutely amazed by how much it has increased my situational awareness when I'm on the road due to its other features.
It warns me through my speakers whenever the speed limit is going to decrease ahead and marks it on the map, displays law enforcement aircraft in my vicinity, gives me police alerts generated by either Waze or Google maps users (still trying to figure out which, or both), overlays a radar heat map generated by crowd sourced data from Valentine One users and it shows me live parcipitation on the map.
I don't consider myself to be much of a speeder but it's very important to me that I keep my no moving violations streak since 2005 going.
John Boy accepts free will donations so it can be used at no cost.