In my experience, the mom blogs are probably the most active (and interesting) part of the blogosphere.
I think this whole gender is wildly underserved, but especially mothers with kids 18 and under...there's huge money to be made building services/communites around these specific needs. BlogHer, etc, is good but just the tip of the iceberg.
Another similar demo is teachers. Trying to "reinvent education" is great but the the meantime millions of teachers and millions more students are underserved and struggling.