Sons of Liberty is a set of free wargames rules for miniatures games set in the American Revolution. Author Wes Rogers also offers a play sheet for reference. The scale is 1 figure=20 infantry.
Legio Quaternarius Ancients Rules
Legio Quaternarius is a set of free wargames rules for ancients. It is played on a square gridded table.
Pirate Figures Comparison
Frothers United, UK has this page which compares various lines of miniature wargaming pirate figures.
No Limits Science Fiction Rules
No Limits is a set of free wargames rules for tabletop battles in science fiction universes. Any miniatures from any game can be used.
Using A Wet Palette
Two good videos on using a wet palette for painting.