I found this lovely erotic comic (many parts NSFW, obviously) the other day. It's the right balance of plot and sex, the drawing style is charming, and it's neo-Victorian sci-fi to boot! My fave.
I'm not sure why I enjoy the idea of robot sex or mechanical sex. I suppose a lot of it has to do with being a sci-fi geek (or am I a sci-fi geek because I enjoy robot sex? :o), and with the fantastical nature of it. I mean, how wild is having sex with a robot, amirite?
Looked at from another angle, I like the idea of being hooked up to a sex machine and being completely helpless while forced into the throes of ecstasy. Ties back into my "mad scientist" fantasy, I suppose.
Though the real-life "sex machines" that I've seen available have been kinda "meh" for me. Maybe it's one of those things that's much better in my head than in real life.