California

• San Francisco Bay Area: Parent Groups in the San Francisco Bay Area
• Los Angeles: Peachhead
• San Diego Parent Connection Group http://groups.yahoo.com/group/parentconnection/

• Ann Arbor, Michigan arborparents - yahoo group - see yahoogroups.com

• Boston - Charlestown Mothers Association http://www.charlestownmothersassociation.org/

• Boston - GardenMoms http://gardenmoms.findsmithgroups.com/

• Chicago - Neighborhood Parents Network of Chicago http://www.npnparents.org

• New York/New Jersey area
  
  See List of Parenting Groups maintained on the Park Slope Parents website

• Portland, Or. urbanMamas online blog for parents in the Portland area

• Washington, DC - DC Urban Moms www.dcurbanmom.com

Other places to look

• Meetup.com start a neighborhood group
• yahoogroups.com (look for small neighborhood and school-based groups)
• craigslist.org (discussions, babysitters, for sale, more)
• google "parents network [your city]"

See also

• How to Start a Network like BPN