There are tons. Just type "Adult Search Engine" in Yahoo. Most require a recip link.
The one's I've gotten in/applied to be in: Booble.com, Pornscooter.com, Cumseeker.com, Wherethefuck.com, exstasia.com,
http://www.sexworld.co.uk/, iwantmyxxx.com, Eroticsurf.com, and Freesexwebsites.com
I don't know if there's an autosubmit.