It's probably well-known that this site;
http://www.tfgamessite.com/index.php ,has free transformation games, 90% of which have TG content, but I thought I'd point out two that have considerable depth TG-wise, since there are hundreds of games to go through- "The Weekend"
http://www.tfgamessite.com/index.php...iewgame&id=570 , and "The Masculine Mystique"
http://www.tfgamessite.com/index.php...viewgame&id=82 .
Not sure if there are any others like them there.