An Hour of Wolves and Shattered Shields has a set of free printable decals for Ancient Greeks. You can print these on decal paper, or on regular paper and glue them to the models.
The Miniature Wargaming Editor
Free Roman Shield Decals
An Hour of Wolves and Shattered Shields has a set of free Roman Shield designs for decals. Just print them out on decal paper, or on regular stock and glue them to the models. I should think that a hobby product called Modge Podge would handle that task well.
Free Viking Shield Decals
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.
Renaissance Naval Rules
David Heading offers a set of free wargames rules for Renaissance Naval Battles.
On To Waterloo Napoleonic Rules
On To Waterloo are a set of free wargames rules based on the On To Richmond American Civil War rule set.