The OGL series by Mongoose Publishing gave us completely self contained games based on the d20 system tailored to fit certain genres less well known to the average roleplaying beginner.

OGL Horror: http://www.scribd.com/doc/36256720/Mgp6602-OGL-Horror-Oef

OGL Steampunk: http://www.scribd.com/doc/69235602/OGL-Steampunk

OGL Ancients:
http://www.scribd.com/doc/70167871/OGL-Ancients-Mythic-Greece-Egypt

All of the above are available on Scribd for either online reading or PDF downloading.

I'd managed to find OGL Cybernet once, but for some reason I am no longer able to.

Anyway, if anybody has links to the rest of the series, that would be much appreciated.

There's the aforementioned OGL Cybernet, OGL Wild West (could never find it on the internet, but surely it's out there somewhere) and the most elusive and mysterious of them all, OGL Manga (of which practically no information exists whatsoever on the net)

Have fun!