The PDF version of the second edition of Starships and Spacemen is available in PDF from RPGNow. The second edition rules are compatible with Labyrinth Lord, which means they are basically compatible with all TSR editions of D&D, their clones, and similar games. Like the original version of Starships and Spacemen, the second edition is designed to loosely emulate the a very popular television series (either the original series or later versions). My only complaint is that the rules are not OGL. The rules are well worth the $6.45 price of the PDF.