I was also shampoo free until I started tri training. Now I shampoo only after swimming with a chlorine neutralizing shampoo. I then apply a rich conditioner and do not rinse it out until the next morning when I take my regular shower. It's not a good as being completely shampoo free, but it's do able.

For me, I went shampoo free to improve my curls. I stayed shampoo free to help the environment, actually. I had a pixie cut and could easily have handled shampooing (no curls when my hair is that short and getting cut every 3-4 weeks!) but opted out.

I 100% agree that water quality plays a BIG role. I started this when we lived in NC and had city water and it was ok. My hair saw big improvement when we moved to our house in Oregon (not so much in the apartment with city water) where we now belong to a local water co-op. When I would visit my parents in FL? ICK! Their water is softened and it could NOT rinse out the extra oils. After only 2 showers there, my hair was a flat, dull, greasy mess!

Another great resource (including lots of make at home recipes for rinses, conditioning treatments and the like) is the book Curly Girl.