A great one that hasn’t been mentioned yet: Salma Hayek and Antonio Banderas in Desperado.
I skimmed this and didn’t see it, if I missed it, apologies. what about Don’t Look Now (1973) - the scene with julie christie and donald sutherland. rumour has it they actually did it.
Just saw the gym boinking scene in Porky’s. That was memorable.
I like the William Tell scene from A Clockwork Orange…
Coming Home with Fonda and Voigt(sp) I heard a huge sigh in the movie theatre when it was played.
Second on Don’t Look Back
Mississippi Masala. Denzel Washington and Sarita Choudhury. Exquisite.
Also the scene in the artist’s hut in another Mira Nair film, Kama Sutra: A Tale of Love, was truly hot and lovely. In fact, that one may have been the best ever.
Heh, you’d be accused of being a pervert if it was filmed as it was in the book - the girls were 11.
The Flower scene in The Wall
I’m going to go with Hup and Plnnr (is that right? :)); “Body Heat” has remained, for me, the most singularly sexual, non-porn movie I’ve seen. Back when it first came out in 1981 (I think), there weren’t that many mainstream (i.e. non-porn) movies that dared to show something that explicit. I have to admit, the scene where they’re in the tub, from behind … now that was so hot, that I was feeling uncomfortable about how turned on I was getting in a crowded movie theatre! 
And the Michael Douglas/Sharon Stone scenes in “Basic Instinct” sure looked damn real to me. LOL More real than many porn films! Not that I’ve seen that many, mind you! 
Very difficult: is the criterion that the scene is realistic, physically exciting, visually witty, or what? On balance, I also vote for Body Heat, mainly because the scenes were both exciting and realistic, but so in keeping with the wonderful style - you could almost feel the humid heat - permeating the whole movie. I’ll second other previously mentioned choices: Name of the Rose, The Piano, The Hunger, Wild at Heart, Delicatessen, and add … errrm … Sea of Love, Dead Ringers and Cat People.
Anyone seen the movie Thursday?
There’s one scene where the protagonist (a man) is tied to a chair and raped by Paulina Porizkova.
'Nuff said.
Greta Scacchi, who was never, ever shy on screen.
That’s probably my favorite nude scene in any film. As far as sex scenes, I like Alyssa’s scene w/ Jonathan Schaech in Poison Ivy 2, when he presses her against the shower door. The similar scene with Bruce Willis and Jane March in Color of Night is also a big fave.
I second this. Dear freaking god, that was a steamy scene that went on forever.
-A2K
One of the best early realistic sex scenes (like Body Heat) was “Rancho Deluxe” with Jeff Bridges and Charlene Dallas. They were out in the wood and going at it full steam, sweating profusely, with her in “cowboy” position. Then while she’s got her eyes closed, Jeff slips a Halloween mask over his face, so that when she opens her eyes again, she screams. Next scene is her chasing him naked through the woods, throwing things at him and calling him names while he laughs and apologizes.
Also, a very tender and kinky love scene in the erotic thriller “Over the Wire” with Griffin Drew putting on some handcuffs while makng love to her sherriff hubby.
I’d have to go with Sea of Love, Body Heat, Basic Instinct, Witness, and The Thomas Crown Affair. All of them possess qualities and scenes worthy of be declared a “Best” award.
>To round out my top 3, there’s the previously mentioned Enemy >at the Gate, and Name of the Rose, but I also was to nominate >Rob Roy.
>Liam Neeson and Jessica Lange went at it fully clothed, and I still couldn’t walk…
Ahhhh…Rob Roy…drool
I’ll also second Better than Chocolate.
I’d also like to mention Velvet Goldmine for the layered “Baby’s on Fire” scene, Ghost for the pottery scene, Pillow Book for just about everything, and the “oooh, that’s just not right!” scene in Galaxy Quest. 
I’d also like to nominate Fire, which may not be that mainstream, but it’s not porn, so what the hey…
I vote for Meg Ryan having “sex” in the restaurant in Harry Met Sally…
How about Ralph Fiennes and Julianne Moore in The End of the Affair…?
Juliette Binoche and John Hurt in Damage.
Oops.
I meant Juliette Binoche and Jeremy Irons in Damage (a/k/a Fatale).
(Obviously, it wasn’t the male lead who got my attention.)