Ravenfeast is a set of free wargames rules for skirmishes in the Norse sagas.
Legio Wargames offers Shieldwall, a set of free wargames rules for Dark Ages battles in the British Isles and Northern Europe.
Crusader Miniatures has a painting guide for Vikings.
Viking Raid is a set of free wargames rules for carrying out a competitive Viking raid. The set uses playing cards as an integral mechanism.