Are there any situations where sex makes a difference, other than romances?Spoilers.

[Pyrenk]

The title should explain it. Conversation choices, entire conversations, quests, and the like apply. I'm asking about the entire series.

[Sir Degrader]

In the copper Coronet, there is a guy who hits on all female NPC's and PC's, that's the only one I know of.

[mad=dog]

I have only played females so far, but one would think it mattered in the Underdark. Being as matriarchian as it is.

[Pirengle]

I'm assuming you mean gender rather than intercourse.

Spoilers ahead...
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covering most of SoA...
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--The male elf in the Copper Coronet hits on women and doesn't really talk to men. (Try hitting on him as a female and agree to whatever he's saying--the dialogue gets interesting.)
--Romances, obviously. Although Anomen is the only Bioware-created romance that gives different introduction dialogues depending on gender. ("Strangers! Perhaps you have more courage than the worms that frequent this pit of corruption" versus "Fair lady, what brings you to this cesspool of corruption?". I think Anomen says his female dialogue regardless of the PC's race--I think it just looks at gender and not romance possibilities there.)
--During the Mae'var quest, a female character with high CHA can acquire the documents from the guy in the Sea's Bounty by flirting with him.
--Males have a chance to sleep with Phaere. Don't know why anyone would want to, but still. Makes anyone the PC's ever been with (or slept with) upset. Viconia takes it in stride.
--I can think of a few other minor variations depending on gender, but I think they're only worth a couple lines of dialogue, and not major game-affecting decisions.