Waze

The most important feature of Waze is not the GPS routing for the drivers, but the traffic feedback that allows the application to reroute people on roads less traveled in order to avoid jams. When a user chooses a destination, Waze takes into consideration the traffic that has been reported and tries to offer a better solution. Most of the time is correct and the time estimates are right on point.
 
There is also a social component to the application. Drivers get points for doing useful things, like reporting hidden radars, hazards, traffic jams, and so on. When the user gets enough points, a few new avatars and options are made available, which culminate with the ability to edit the map.
 
Waze comes with support for numerous languages, has Facebook integration, offers the possibility of planning drives ahead of time, calendar synchronization, and much more.