Here are 4 additional directories that have returned a high traffic volume for me:
Billy's Links at http://www.billyspervwebsite.com/
http://www.gayplanet.com/gayplanet/s...ervicebis.html
http://www.sindbadbookmarks.com/world/index.html and
http://www.link-o-rama.com/greenguy/email.shtml (a general adult link list focusing on small free sites)

Some of the ones already listed are on my high traffic list too.