A few things (which I won’t link to) came up in a Google search. Does anyone have experience with a good service?
Let’s not provide links here. Perhaps just yes/no answers with hints and opinions?
This is just for a research project, you understand… :rolleyes:
I don’t have any info for you, but I’d like to know about Netflix-type porn, too. 
Simple. Just go to Number Slate, which is a comprehensive DVD rental service just like Netflix, only they have a “Mature” section that contains porn. (Strangely enough, Netflix no longer rents straight porn, but they do have a Gay and Lesbian section.)
DVDovernight also rents them.