I actually have, but I agree its rare. It's marketed as "porn for women" because it has a story and isn't filled with cum shots. The producer is a lady named Erika Lust (http://erikalust.blogspot.com/) and the only film of hers I've seen is called "the good girl" and it's actually won awards. http://en.wikipedia.org/wiki/The_Good_Girl_(pornography)

I hope the porn industry either learns or gets out of the way. =)