Dr. Barry Komisaruk and Nan Wise have been doing MRI scans of women's brains to determine whether or not spontaneous orgasms really happen...and they do.
What I love most about their research is that they're refuting the whole evolutionary byproduct theory of female orgasm (that women don't need to orgasm to get pregnant so female orgasm doesn't serve any evolutionary purpose) by proving that women can experience orgasm by fantasy alone - they don't even have to touch their genitals. It's basically the equivalent of nocturnal emissions in men.
They're research started in the late 90's spurned by a book by Susan Crain Bakos:
"A 1996 book, “Sexational Secrets,” described a workshop on spontaneous orgasm and featured a how-to guide.
At Rutgers, Dr. Komisaruk expanded his research to brain scans. In 2003, the first images confirmed the earlier study. Pleasure centers lit up more or less identically whether the women reached sexual highs by hand stimulation or by erotic thoughts.
Dr. Komisaruk had difficulty finding enough volunteers for a thorough study until he met Ms. Wise, the Rutgers doctoral student. A sex therapist, she turned out to have the right contacts as well as her own autoerotic skills. “It’s the least sexy thing in the world,” she said of having her brain scanned. “But I do it for science.” By early 2010, Ms. Wise and Dr. Komisaruk had succeeded in scanning a dozen volunteers.
Late that year, at the annual meeting of the Society for Neuroscience, the world’s largest group for brain research, the Rutgers team presented a surprise finding that suggested that the scientists were zeroing in on the phenomenon’s origins.
Women who simply thought about the stimulation of their breasts and genitals, the scans revealed, lit up the brain’s corresponding sensory areas."
Personally, I've never experienced a spontaneous orgasm. I have to stimulate my clitoris. But now I have a new orgasm goal :)