The Simplest Turn-by-Turn Navigation System EverS  There's
plenty wrong with turn-by-turn navigation, so here's a
completely different solution: boil the route down into the most
simple set of rules possible, and leave the user to it.  There
are plenty of systems that can be described far more simply than
they initially appear—and directions are one of them. So instead
of just describing which left and right to take based on
distances travelled, an algorithm could boil down instructions
to a simple set of logical rules which can be used to navigate
to the same destination. If nothing else, it'd keep you mentally
alert during the journey. [XKCD]