I have tried to go no-poo (yes, I too thought this was a constipation thread!). My hair was really flat and greasy within a week. So I tried castille soap on it for a couple of months- dried it out horribly. Went back to my (cheap Suave) shampoo (that I dilute 1/2 and 1/2- I hate thick shampoo, I don't feel it gets anything but the top layer of hair) for a couple of months now. I do use WV rinse, but that's more to get the hard water deposits off the hair from our horrendously hard water. I'm afraid it makes my hair smell like a salad, though.
I'm considering trying some of my home made soap on my hair once I get back to a sort of baseline.