Misbehaving.net has some interesting info on website design, and how different things appeal to men and women:

Women seemed to like pages with more color in the background and typeface. Women also favored informal rather than posed pictures.

Men responded better to dark colors and straight, horizontal lines across a page. They also were more pleased by a three-dimensional look

And the unsurprising punchline:

With those standards in mind, the researchers checked out the Web sites for 32 British universities and determined that 94 percent had a "masculine orientation." Two percent showed a female-favored arrangement.

This is probably an argument in favor of having multiple, user controllable styles available on a site...