Most pornstars probably wouldn't like my answer, since I've heard the lady in question is bitch from hell and I doubt most of her colleagues would want to be around her, much less work with her, but I've always wanted to see a Naomi Campbell (in her prime) in a porn movie (or better yet, picture set).
I'd also like to see Nicole Eggert (from her baywatch days) in a porn movie. (& since I haven't heard much bad about her, I doubt most of her colleagues would have trouble working with her...)