A series of routes with a carefully calculated altitude profile, so that when driven at constant speed the resulting power-time graph is similar to the workout that inspired the route, f.i. Amalgam.
It is not really a new feature but I think these routes would be wonderful for groupworkouts, because you can set a fixed speed (which you advertise beforehand, so everybody knows what he’s up to) and keep everyone together more easily.
Of course there should be lots intersections so you can mix up things. Color of environment could change with corresponding powerzone.