An estimated 97.2 million girls and women age 3 and older will be online in 2007, or 51.7 percent of the total online population, according to eMarketer. Internet use by women has increased 12.4 percentage points since 2000, while males' use is up 3.2 points.

This year, an estimated 66.2 percent of U.S. females ages 3 and older will use the internet at least once a month, compared with 64.2 percent of males. By 2011, 72.1 percent of females are expected to go online compared with 69.3 percent of males.

"For girls who have grown up with technology, there is no significant gender gap in internet usage, and the rise of activities that are particularly appealing to young females, such as social networking, will result in even greater usage," said eMarketer analyst Debra Williamson.