I found the Weston A. Price site to be the most helpful and full of good information during my pregnancy and after...I encourage all women who are pregnant or thinking about having a baby to read through their articles on prenatal, infant, and toddler nutrition.
Another good writer on food is Nina Planck (www.ninaplanck.com) -- she writes about the importance of "real foods" rather than what she calls "industrial foods" like soy.