Last weekend more than 2,400 women bloggers descended on New York City for the annual Blogher conference. That was eight times as many as attended back in 2005, in the website’s infancy. The women of Blogher, a website that serves as aggregator and community for thousands of  bloggers, are a varied lot. As I type this the front page features a post on the plight of Hatian orphans, another on the best backpacks for back-to-school, and this one on a new test for Alzheimer’s disease.

And then there is politics. The nonpartisan website welcomes views from the left and right and everywhere in between. Blogher’s founders, Lisa Stone, Elisa Camahort Page and Jory Des Jardins, have been increasing opportunities for Blogher participants to interact with elected officials. Last weekend’s conference brought a visit by Sen. Kirsten Gillibrand of New York, who met with a group of about 25 bloggers (I was one) to take on-the-record questions. Gillibrand’s visit was covered here, here, and by CNN here. Gillibrand answered questions and spoke on topics ranging from cybersecurity to daycare to transparency, restating her support, for example, for posting congressional schedules and earmarks online.

Last fall Blogher organized a bi-partisan series of conference calls for bloggers, partnering with the Sunlight Foundation, to interview Members of Congress questions directly about health care reform. Bloggers were pointed toward Open Congress, where they could read the proposed health care legislation for reference and prepping for the calls. Among the participants were Speaker of the House Nancy Pelosi, Rep. Cathy McMorris Rodgers, Sen. Gillibrand, and Rep. Cynthia Lummis.

Blogher’s power is such that it has attracted corporate advertisers and sponsors that used to be the province of women’s magazines and newspaper pages: McDonalds, Kellogs, and the like. The bloggers themselves, however, aren’t afraid to challenge them–at one discussion I attended, a panelist urged the audience to challenge PUR water filters, who had an exhibit outside, on whether their filters were recyclable.

As traditional news organizations continue to go bottom up, Blogher is one model of how bloggers gathered together can become a force that politicians must pay notice–and how the bloggers themselves are becoming more sophisticated in using online tools to hold them accountable.