When I was pregnant, I read tons of books, went to classes, researched online, talked with every mom I knew, and still I wasn't prepared for mommy-hood.
One of my most valuable resources is a local online listserv that I joined early on called Brooklyn Baby Hui, for moms like me in Williamsburg and Greenpoint. This is a place where I can post any question at all - about pregnancy, about childbirth, about parenting, health, baby gear, things to do in the neighborhood - anything! And the other gals in the neighborhood will do the best they can to share their experiences and point me to other resources. There are also tons of events and activities for new moms to attend. If you live in or near our 'hood, you should join it!
Before Baby L. was born I posted tons of questions on how to find a nanny in our neighborhood, and people sent me recommendations for actual nannies, not just vague suggestions. When I was having trouble breastfeeding, I found support from dozens of other moms who were either having the same problems, or had been through it before. When I wasn't sure what kind of stroller to buy, I was pointed in the right direction (I love my stroller!).
Now that L. is three months old, I find myself answering other people's questions for the first time -about pregnancy, childbirth, breastfeeding. A group of moms have figured out that I'm a reading teacher, and now people email me directly with questions about schools and their child's learning.