Patricia Brennan is an evolutionary morphologist who teaches at Mt. Holyoke College (her website is here), and her speciality is animal genitalia. As the locus of morphological contact during reproduction, one would expect both natural and sexual selection to act very strongly on genitalia, and indeed they have (see William Eberhard’s underappreciated book Sexual Selection and Animal Genitalia). I suppose that because of a stigma attached to genitals, they aren’t studied nearly as much as they should be by evolutionary biologists. Here’s a video of Brennan and some of her work, first published at the xxfiles in Science.
Although biologists have concentrated on male genitalia, as those are often the most easily seen diagnostic features of related insects (that itself speaks to the importance of sexual selection, for why should genitals change so quickly compared to other traits?), Brennan also looks at the vaginas, which, being internal, are harder to see. She uses silicon molds to define their shape.
The male mako shark genitals described at 1:40 are way cool, and the spines on them probably show some kind of antagonism between male and female during copulation: the male wants to hold on to inject his sperm, but the spines don’t allow a female to reject such a male, and may damage her as well. You want more? Read about “traumatic insemination,” evolution’s version of Fifty Shades of Grey.
Brennan specializes in duck genitals, which can often be amazingly long and contorted (see one of her short videos at the Science page).