Washing with conditioner is called "the curly girl method", and you can find a lot of great info about it online. I've been doing it for two years now, and it's fabulous - it's such a change in my hair, it really leaves your curls soft and shiny.
There's a method to it - it's not just slapping conditioner on your hair and calling it good, because then it'll be greasy. You actually use a lighter conditioner like a shampoo - you scrub with it, just like a shampoo. Then you use a heavier condition to condition with. Make sure there are no silicones or sulfates in the conditioners, because they can dull the hair and are hard to wash out. It works great for dry and curly hair, which I have - it's been really great!