Check out this great article called "How Women Work." It's like a combination of Women for Dummies, Everything You Wanted to Know About Women But Was Afraid to ask, and Women: The Missing Manual.
My favorite factoid: men have 6.5 times more gray matter than women. Women have 10 times more white matter. Gray matter is for processing centers. White matter is for creating connections between processes so that people can see and process patterns.
Everyone who wants to stay married or market stuff to women should read this.