Votes for Women 2004 is an organization that tracks the gender gap in voting and the power of the women's vote. Interesting information if you ask me. According to the site this year there was a 7% gender gap in the recent Presidental elections. The next questions is - is 7% better or worse? According to this site the gender gap was 10% in the 2000 presidental election.
Also, on this site is a great list of other sites on both current and historical issues regarding women voting. The list includes some great resources as well (Iron Jawed Angels movie and a book available at Amazon).