PZ8 1950-69 is a set of free wargames rules for using 6mm miniatures to refight battles of the mid to late 20th century.
Rules: Modern
Jihad Wargames Rules For Modern Insurgency
Jihad is Stan Johansen’s rules for modern insurgencies. There also are printable action cards and counters.
Covering Fire! One Page Rules
Covering Fire! is a set of free wargames rules on a single page. It is designed for platoon level actions and uses no measuring tape or turn structure.
Firefight 2050 Rules
Patrick Todoroff offers Firefight 2050, a set of rules for 1/72 figures in a near future setting.
MIG Alley Ace
MIG Alley Ace are rules for modern aircraft combat from 1945 to the missile age.