Pulp Friction is a set of free wargames rules for pulp-style skirmish games. They currently are in playtesting and look very nice.
From the Yahoo Group:
Void Trek 3007 A.D. is the free downloadable space opera roleplaying game. Void Trek is for those who like two things, old fashioned SF and simple, 1980s style roleplaying rules. The entire rulebook is 11 pages long (INCLUDING the errata sheet), and it is set up to get you playing within an hour (no joke).
So, if names like Flash Gordon, Buck Rogers and Rocky Jones stir your heart, if the idea of saving swooning green skinned (but hot…) space princesses from bemuscled villains with scales and eye tentacles is what you are all about, please download the rules from the files section.
Pulp City is a set of free wargames rules for pulp, super hero, tv series and B-Movie adventures.
Tackling a Tyrant is a set of pulpy dinosaur hunt rules for 28mm figures.
Here are a set of free wargames rules for conducting a Dinosaur Hunt.