American Girl Outsider: Crafting Creatively: Get Your Knit Together
This is a very informative and helpful post on crocheting and knitting for dolls. I crocheted a few things for my dolls and they look hideous. Now I know why. I'd suggest that anyone new to knitting and crochet for dolls read this before getting started.
She explains what to do and what not to do and shows you with pictures. Very helpful.