When playing the board game, Burning Banners, my friends and I had a hard time determining, at a glance, which faction controlled which settlement, so I created some hex outline markers, which can be printed or painted in each of the faction colors.  There's one plain hex outline marker, and one marker with modeled flames (to represent a settlement which has been razed).  The markers will fit just inside the edges of a hex on the board, with army tokens fitting inside (I've printed and tested!).