Working moms, have you networked through the Downtown Women's Club? I haven't but I like the idea of an all-female networking group -- it seems to level the playing field a bit. And I definitely think that having a job-search buddy or networking group makes you more disciplined about career advancement.
In any case, I like the Downtown Women's Club official blog, the womensDISH, and I'm making it the About Working Moms Site of the Week. Like all group blogs, you'll find a mixed bag of perspectives and information. I find the posts generally uplifting and helpful, and the "bookshelf" contains several business books that I've read or have on my to-do list.
The site isn't specifically aimed at working moms, but I think you'll find a lot of common interests. Please share your thoughts with me if you visit!