This is a couple years old now, but I thought it was interesting nonetheless:

http://www.nytimes.com/2009/01/25/magazi...nted=print

It talks about a few different researchers who are studying female arousal and the data they've collected. Some of this falls in the "duh" category (like female arousal being more complex than male arousal--no, really?), but some of it's pretty interesting. For instance, there's a disconnect between what women believe arouses them and what they actually respond to on a physiological level. Also, there's this, about why women tend to become less attracted over time to men they're in a relationship with:

Quote:And within a committed relationship, the crucial stimulus of being desired decreases considerably, not only because the woman’s partner loses a degree of interest but also, more important, because the woman feels that her partner is trapped, that a choice — the choosing of her — is no longer being carried out.

However, there's an important qualification to this as well:

Quote:Yet while Meana minimized the role of relationships in stoking desire, she didn’t dispense with the sexual relevance, for women, of being cared for and protected. “What women want is a real dilemma,” she said. Earlier, she showed me, as a joke, a photograph of two control panels, one representing the workings of male desire, the second, female, the first with only a simple on-off switch, the second with countless knobs. “Women want to be thrown up against a wall but not truly endangered. Women want a caveman and caring. If I had to pick an actor who embodies all the qualities, all the contradictions, it would be Denzel Washington. He communicates that kind of power and that he is a good man.”

It's a long article, but worth a read.