The Singer Not the Song is an obscure British Western set in a Mexican village where everyone speaks with an English accent. Dirk Bogard is a black-leather-sporting bandido, and John Mills is a priest (work with me on this). At the end they both get shot and they sort of sprawl around holding hands. It's mental, but great.
Get Carter is the best film ever. Michael Caine is a psychopath seeking revenge on his brother's killers. In the scene I'm thking of, he is in bed with his landlady when the thugs walk in to 'ave a word'. Caine rolls out of bed, naked, and comes up from behind the bed with a shotgun. It's poetry in motion, I'm telling you.
Alien needs no intro from me. Sigourney Weaver in her vest and pants.
Blade Runner Same director of course. Harrison Ford snogging Sean thingummy, the android. That whole scene is way hot, starting from when he slams the door shut with his fist.
eXistenZ The first non-British director I've picked, Cronenburg, with a virtual reality thing. Now, there are two very sexy scenes in this film. Willem Defoe assaulting Jude Law with a massive cable is pretty fine, but my favourite has to be Jude putting his tongue in Jennifer Jason Leigh's bio-port.
The Fellowship of the Ring. Well, I don't want to seem too gruesome (ha) but the whole sequence from when Boromir starts getting hit by arrows is pretty exciting. The best bit for me, though, is when Aragorn hits that Orc creature from side-on and knocks him down. It's inspiring.
There must be so many more. Suggestions welcome.