IIRC in the US women drive about 80% of purchases, meaning each female user is worth several times what each male user is worth. In terms of communicating the value of the business to investors, the fact that the userbase is mostly female is arguably the most important aspect of the site.
I don't have a good cite, I believe it's supposedly all purchases though. Not sure how accurate it is, but my understanding is that sites with a lot of women do have vastly better clickthrough rates and conversion on their ads so it's not entirely apocryphal.
