Check out Rockland Moms on meetup.com. I've been a member for a while and it's such a great group of women. There are tons of events (especially if you're a SAHM, which I'm not, but there are still lots of things to go to) and the message board is pretty active.
I dont know where you live but there are some great programs that the Town of Clarkstown provides. I work for the Park and Recreation Dept. Page me if you would like more info!
Re: Play group recommendations please!