Brian Gill offers Bugs!, a set of miniatures rules for staging battles with large numbers of plastic insects.
rules
The Caveman Clash Manual
Caveman Clash is a set of free wargames rules for playing skirmishes between cavemen. There also are paper figures if you don’t happen to have cavemen available.
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.
Impetus Basic Rules Update
There’s been an update for the free basic rules for Impetus, a set of ancient and medieval wargames rules.