Women are the primary shopper. Women control almost $12 trillion of the $18 trillion in global consumer spending (Nielsen.com, June 15, 2010). Women in the US control 73% of household spending (Boston Consulting Group, 2009 p.21)
On a typical day, more men watch a YouTube video than women – 23% to 15%.
Lisa Finn of Lucid reported in 2010:


Women are more likely than men to sign up for emails in order to obtain deals and promotions (67 percent compared to 57 percent).
Women will respond to a bad ad. Here is an example of what happened to Motrin.