SHAMpoo that is.
NPR had a segment on the anti-poo movement. This site has instructions on using baking soda and vinegar instead of shampoo.
I shampoo my hair every other day. Sometimes I will go three days if it isn't looking too bad. Currently we are using up samples in our house (yes...we have been doing this for over THREE MONTHS now) so I don't have a particular brand I am using, although we try to get one without sulfates. Since I have dry everything (skin, hair, nails) I noticed that my hair was much better when I stopped shampooing every day.
I don't think I could totally switch to baking soda and vinegar. I like the smell of commercial shampoo too much.