Sistaslick and Gymfreak. Whenever I read their posts I pay close attention b/c I know they are telling the truth.
They both know a lot about the chemical makeup of the hair strand/hair products and do great jobs of what really happens to the hair when you do x, y and z.
I was going to say them, too. I've referred others to info they post. Also NaturalGirl for homemade stuff and Nonie for 4b management tips and techniques and braids.