I love the D6 books from West End Games. Now they're supposed to be called Open D6 and they are now available in many places including DriveThruRPG, which makes it seem more official than downloading it off of a fan site. I'm referring to D6 Adventure, D6 Fantasy and D6 Space.
Built from the D6 System that powered the original Star Wars RPG, but originally debuted with the Ghostbusters RPG, more or less. WEG continued to develop it as a generic system after the Lucas Arts license moved on.