But even after all that ranking, weighing and debating, we'd be hard pressed to define exactly what it is that makes a sex scene great — in true Justice Potter Stewart fashion, we just know it when we see it, whether it shocks us, titillates us, turns us on, breaks our hearts or confounds our expectations.

The oldest film on this list is from 1896; the newest is from last year. You'll notice we decided to leave certain standards in the field off. And as always, these lists are a launching point for you to tell us what you think. Are we wrong? Are we right? Did we neglect the sexiest sex scene ever? Tell us in Feedback.

We'll be launching ten movies a day, counting down to #1 on Friday.

50. Ken Park (2002)
Oh, Larry Clark, what oversexed minors are you discovering/exploiting this time? Ken Park's most well-known scene is the boy-on-girl-on-boy oral-sex fest toward the film's finale, and it's kind of disturbing and kind of fun. These kids are young, which makes you feel a wee bit lecherous about sitting in a theater and getting turned on amongst a couple hundred strangers who are doing the same. But what can you do? The fact that the scene concludes with a tickle fight that wouldn't be out of place in a PG movie about summer camp (were the participants not totally naked) doesn't help. But then, making us feel just a little weird about ourselves is what Clark has always been good at. — Will Doig  

49. Laurel Canyon (2002)
This film's much-ballyhooed threesome isn't as pitch-perfect as Kate Beckinsale and Christian Bale's opening sex scene, all awkward and tender and on the verge of a possibly ill-conceived marriage. Bale's character is going down on Beckinsale's, following her highly specific verbal instructions in what we can assume to be a foreshadowing of their lopsided wedded dynamic. It's great when a sex scene can actually say something about the characters' inner lives and not just steam up the passenger window of a Model-T in cruise ship cargo hold. Beckinsale finally orders her fiancé to "fuck me," only to be interrupted by an answering machine from her future mother-in-law. In the end, she orgasms and then asks Bale if he came too, to which he sighs and responds, "I'm okay." — Will Doig  

48. Fur: An Imaginary Portrait of Diane Arbus (2007)
It's easy to forget the inherent sexuality of the Beauty and the Beast metaphor in these Disney-fied times — that the contrast between glamorous and grotesque generates palpable erotic friction. Fortunately, screenwriter Erin Cressida Wilson and director Steven Shainberg (the team behind 2002's SM love story Secretary) tease out the fairy tale in Fur: An Imaginary Portrait of Diane Arbus, a whimsical biopic that renders the photographer's muse a fictional, hirsute Lothario named Lionel (Robert Downey Jr.) who introduces Arbus to a world of photogenic imperfection. Compared to James Spader's dominant persona in Secretary, Lionel brings less insecurity to the table, blindfolding Arbus (Nicole Kidman) while confidently drawing her in to his sexual universe. As opposed to to the confused, frenzied fucking between Arbus and her husband in the film, the Lionel/Diane sex scenes possess a surprising tenderness despite the kinky power exchange. Hottest of all is the scene where Arbus shaves off Lionel's fur — there is something tender yet carnal, loving yet bestial about the entire exchange — to say nothing of the powerful contradictions in Arbus' photographic oeuvre. — Jessica Gold Haralson 

47. The Dreamers (2003)
Maybe it's because we live in an age where blood in the midst of intercourse can be dangerous, but of all the sundry sex acts in The Dreamers, the blood-on-the-face scene is the most memorable. (Some would argue it's the scene where the three young stars literally bathe in a bathtub filled with menstrual blood, and they'd have a solid argument — we say that's a close second). Bertolluci is no stranger to envelope pushing, and though we found this Boomer-made movie about the wonders of 1968 to be a tad preachy, you've got to give him credit for letting young, naïve American Matthew break a hymen on screen. When Matthew (Michael Pitt) then reaches up and smears the virginal blood on his partner Isabelle (Eva Green)'s face — and then her brother does the same — a sex scene that we'll never forget (for better or worse) was born. — Will Doig  

46. Sex Lies and Videotape (1987)
"I've never really been that much into sex," Ann (Andie McDowell) tells her therapist at the start of Sex Lies and Videotape. Repressed and unhappily married, Ann changes her tune when she meets her husband's reclusive friend Graham (James Spader), who considers himself impotent. Graham's only sexual gratification comes from videotaping women while he questions them about their sex lives; his video collection horrifies Ann and hopelessly intrigues her. After a series of confrontations that leave them both emotionally naked, Ann turns on Graham's video camera and approaches him from behind. Boldly, she guides him to a couch and kisses him. Graham looks alarmed for a moment, then succumbs, then does something truly surprising: turns off the camera. — Gwynne Watkins