Richard Florida, author of "The Rise of the Creative Class" and "Who's Your City?" has posted some very interesting demographic information profiling cities by their balance of men to women. The map is intriguing in that it shows a pronounced east west divide with more single women east of that line and more single men west of that mythical line. Data is for singles ages 20 - 64.
I'd love to see an overlay of other geodemographic information about women-owned businesses, patent filings etc. to see how this correlates with other business information.
The data has some interesting implications for consumer marketers targeting singles of either gender.