I pay frequent visits to Parenthacks, not so much for advice, rather to follow the conversation.
Along the same line comes Maya's Mom which combines other parents tips with suggestions of activities in your area or at home.
They guess your location vased on your IP address.
Maya's Mom also hosts Parent Groups such as Dads with Daughters and Parents with Pets which according to them work with existing Yahoo Groups.

To add to this topic let me also mention a New Jersey based site called Parental Wisdom,the creation of Tina Nocera who I have known for a number of years.

I guess today with this post and the previous on Book Exchanges, I am on the Parent Track.