Blogs are the most influential social media for U.S. female internet users while social networks are the most popular, according to the 2009 Women and Social Media Study (pdf) by BlogHer, iVillage and Compass Partners. "The scale of social media usage among U.S. women continues to grow, and blogs remain the go-to resource for those who want to gather information, share ideas and get reliable advice," said Elisa Camahort Page, BlogHer co-founder and COO. 42 million women in America use social media at least once a week, which is 53 percent of the U.S. female online population. (For the purposes of the study, social media is defined as social networks, blogging, reading blogs, posting to blogs, message boards and forums, and status updating.)

The most popular activity is social networking, which is done by 75 percent of online females. Second is any kind of blog activity (writing, reading, commenting), which 55 percent do.

Blogging, which has the highest penetration of all social media activities, has the biggest influence, as blogs are more likely to report on new trends and have tech-savvy writers and readers.

“Bloggers have a broad reach in the social media population and the survey demonstrates that women who blog are the most actively engaged social media participants -- constantly seeking out new ideas and ways to share their opinions about those ideas,” said Susan Wright, President of Compass Partners LLC.

Following blogs in influence are message boards, used as often as blogs for finding new products, but having a less tech-savvy audience and a lower frequency of activity.

The least influential is social networking, which has a broader reach but smaller penetration than blogs, as users are the least active in any social networking category.

By Mark Alvarez