I'm doing something in between gido and ender.
Before, I would shampoo every day and condition with good quality salon brand products. My hair was always dry and poofy. I had to keep it cut short to keep it under control, or I would have to use lots of pomade or other product. Even then, with longer hair, by the end of the day my hair would be like crazy caveman Einstein hair. If I skipped washing one day, my scalp would be itchy and oily, and I would get crusty/dandruff-like stuff forming.
I started washing my hair with shampoo less frequently a couple of months ago. At first I would skip one day, then two ... now, I'm washing about once a week. I switched to a sulfate-free shampoo with argan oil by DermOrganic. I use very little - just enough to break up the sebum on my scalp - no heavy lather. I condition one day mid-week. The other days, I wash with hot water alone, gently scrubbing my scalp with my fingertips, and combing through my hair with a fine tooth comb under running water. I rinse with cold water (thanks, gido!)
When I get out of the shower - even washing days - my hair slicks back when I brush it as if it had vaseline or a waxy pomade. It's waxy enough that it feels almost like a solid shell when I brush it all back. My wife jokes that it's like I'm producing my own styling product now. It may sound bad, but it doesn't smell at all when I get out of the shower. When it dries, it fluffs up nicely. It gets wavy with some body, and feels soft and healthy. It's looking like Gabriel Byrne's hair a little bit as I'm starting to let it grow out now. It always feels like I used a deep conditioning treatment, it's easy to manage all day with no product, and it doesn't feel oily or greasy.
By the end of the day it smells a little "animalic", but no worst than when I was washing every day. It doesn't get itchy now.
I'm very happy with my new routine. I'll never go back to washing every day. It feels like I've been paying to trash my hair all these years. If you haven't ever tried it, I think you'll be surprised by the results. I was skeptical and very pleasantly surprised. The transition can be hard while the scalp adapts to not being stripped squeaky clean every day, but tough it out a few weeks and you get past that.
I started doing the same with my kids. I wash their hair about twice a week - anytime it smells. Their hair feels very nice and soft now and doesn't tangle. My daughter has fine curly hair, and she used to wake up with it tangled and matted - now it brushes out easily and is soft and silky. Full disclosure: my wife thinks her hair is not as shiny, and that shininess is "very important for girls".