Here’s a nice — if not overly deep — painting guide to ancient and medieval armies.
medieval
Late Medieval Skirmish Rules
The Late Medieval Skirmish Rules is a set of free wargames rules for large scale figures on an actual dining room table (with salt shakers, etc.)
Jousting Tourney Rules
Al Hewitt and Ric Willey offer Jousting, a set of free wargames rules for medieval tournaments.
Argad Medieval Skirmish Rules
Argad is a set of free wargames rules for skirmishes in the dark ages and for pirates in the 17th and 18th centuries.
Medieval Skirmish Rules
Richard Bradley’s Medieval Skirmish rules are offered for free on the Tyneside Wargames Club site. There actually are quite a few free wargames rules there. All look quite playable and fun.