Just eight years ago, females constituted only 45 percent of Internet users, but according to a just-released eMarketer report, "Women Online in the US," females made up 51.6 percent of the US online population in 2004.

Adult women dominate consumer spending offline and are increasingly shifting to online shopping. eMarketer projects that the female majority will grow over the next five years, transforming online content, commerce and marketing.

As the female influence grows, companies will need to appeal to females through word of mouth marketing, email and relationship building, the eMarketer report concludes.