Proposed features/Motorway,Motorway Link
I'm using this key for "k='highway' v='motorway'" and "k='highway' v='motorway_link'" to explain the direction of that way.
For motorways, it shows the general direction (east/west/north/south) that isn't always obvious if you see only a small section of the map. (thats also the way, traffic jams are reported on the radio)
For motorway links it shows which wotorways are connected.
k='highway' v='motorway' k='highway' v='motorway_link'
maybe also for trunk/trunk_link
k='highway' v='motorway' k='direction' v='W'
k='highway' v='motorway_link' k='direction' v='A67S -> A6W'