first, the erotic. i recommend (as a matter of policy) walerian borowczyk, in particular the contes immoraux. these are four short films, each one a little gem: impeccable sets, music, humour, women, objects, perfection in short. impossible to watch this and not be aroused and elevated in equal measure.
and porn, as per bangpuss' request. i think it's possible to have sex, with sounds and bodily fluids and so on, very explicit, filmed in such a way that transcends mechanical porn, becoming something of worth while achieving the primal excitement/lust that is the whole point of porn. for me there are two forms that do this: one naturalist, sex as-is without artifice, with emphasis on feeling and pace, the other fantasist in the libertine tradition, with elaborate perversion or inversion of the social order. i can recommend some fabricated things along the lines of the above, two japanese, two australian:
tohjiro's mourning dress sisters, 2003
two sisters lose their parents and find solace in each other. sloppy kissing, fondling, flogging each other with flowers, plaintive moaning, etc. ensue. it's drawn out, languid, absurd, and it works beautifully.
clockwork orange lesbian edition, 2007
sadistic lesbian warden/guards torment the female contingent in this dystopian women-in-prison-type thing. much flogging, forced sex and general nastiness befalls the unlucky prisoners, who accept their fate with surprisingly tender resignation.
abbywinters' beck & lea, 2008
two normal-looking girls having sex, looking very comfortable with each other, birds chirping in the background, sunny room, etc. at their best, these videos are cute, tasteful, explicit and sexually arousing at the same time.
abbywinters' cleo and larissa, 2009
this one sees a couple in a coffee shop, closeups of lips, eyes, gestures, kissing on the way home, a build-up that enhances the effect of seeing the girls in bed later in the video.
in general i find the david hamilton school of languid pastoral nudity ideal, even the less inspired hamilton-derivative disco-soundtracked 80s stuff like chris nikolson's lovely vhs magazine is worth watching. the more recent examples of this are derivative and kitsch along the lines of galitsin, and need to be muted because of the russian penchant for horrible techno, but worth watching if you're desperate.
there are oddities that are not really porn, but borderline pornographic, koji wakamatsu's embryo hunts in secret comes to mind.
there is also a lot of seventies/eighties middle ground semi-pornographic and surreal-pornographic stuff that is interesting: the carefree post-franco debauchery of la caliente niña julieta, the crass, inept porn of jess franco, le sexe qui parle, the porn-infused cinema from stylish to crass with leonora fani, ilona staller. some not necessarily exciting, but interesting visually and as artifacts of the time.
so there you have it, porn and stuff. clearly i have a lot of time on my hands.