I wonder if it makes sense to have threads which everyone can read but only those can post who've chosen "female" in profile?
It won't stop deliberate creeps but will make it harder by a few clicks. What's more important, ladies might feel more secure, and we'll enjoy their company more ^_^
It could be like a user role: those who've chosen "female" can post to any thread, while others can post only to some. On the interface it might be a tag or a checkbox