The BabyWearer: The best source of information for all things babywearing. Reviews of different carriers and vendors, directions, a great forum, and scads of other stuff. (I'm listed as sleeping baby productions or SBP, and post as Jan Andrea.)
La Leche League International: The most well-known pro-breastfeeding organization; provides free and useful information on breastfeeding issues.
misc.kids.breastfeeding (MKB) newsgroup: A usenet group devoted to topics concerning breastfeeding. This newsgroup has been absolutely invaluable to me, and I highly recommend it if you are pregnant, nursing, or partnered with a nursing mother.
Plus-Sized Pregnancy Website: If I were religious, I'd call this site a godsend for zaftig moms-to-be. "Kmom" has compiled tons of information on what to expect, finding a size-friendly practitioner, nursing with big breasts, and lots of shopping resources. I found it absolutely indispensible while I was pregnant.
Gentle Christian Mothers: Friendly, Christian-oriented attachment-parenting forum and website. A nice change from supposedly Christian parenting "experts" like Ezzo (who, in a nutshell, believes babies should suffer because Christ did). (Hey, I may be an atheist, but I know not all of my readers are :)
Nandu sewing patterns: Andrea Noll is a Hungarian mom, midwife, and seamstress. She offers a number of patterns for parents and kids.
Make Baby Stuff: Baby crafts tutorials, instructions for how to make baby clothes, how to make baby toys and tons of DIY crafty projects for all things baby! Your how-to resource for baby's homemade lifestyle.
Yahoo Groups:
Babywearing: Talk about babywearing, favorite carriers, etc.
Babywearing Swap: Carriers for sale or trade
Sling Sewing: Talk about sewing carriers, patterns, etc.