An Hour of Wolves and Shattered Shields has a selection of high resolution shield designs for Vikings. Either print them out on decal paper, or on regular paper and glue them to the model.
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.
Age of Blood is one of the best set of rules available for free on the internet. Heck, its one of the best available at any price. Designed by Tom Hinshelwood, the second edition rules offer a complete game and campaign system for the age of Vikings.
Age of Blood is a skirmish-level battle game in which players take control of bands of Vikings and lead them on bloody adventures in search of loot and glory. These rules contain all the information you will need to know in order to play either one off games or complete campaigns. The game is designed for use with 25mm or 28mm miniatures, though any individual based model from 15mm to 40mm can be used. Play is possible with any scale but distances and measurements would need to be proportionately reworked. Age of Blood�s focus is on the fantastical aspects of Viking history and as such is more concerned with the legends and heroic sagas then trying to depict a realist view of the era. These rules are loosely set in the 9th Century, though the supernatural is prevalent in many aspects of the game including fate, magic and monsters. If desired though the supernatural elements to the rules can easily be ignored so that the game can be played as a purely historical wargame.
Other Age of Blood Resources: