Star Wars Silent Death is a set of modifications for the excellent Silent Death rules for the Star Wars universe.
Boonta Eve Classic is a set of free wargmes rules for pod racing in the Star Wars Universe. The rules are designed for use with those old Galoob Micromachines, which can still be had for a reasonable price on Ebay:
Star Wars Shootout is a set of free wargames rules for skirmish combat in the Star Wars universe.
This video has some really nice ideas for making cheap terrain for Star Wars Legion and other science fiction games.