My new friend Martha swears by her weekly apple cider vinegar rinse. She simply mixes a concoction of apple cider vinegar and water up in a spray bottle and she sprays it on her hair after she shampoos and conditions. (Get the recipe here).
Apparently the acetic acid found in the vinegar helps wash away shampoo/conditioner build-up and vinegar is a natural dandruff fighter. If you do try this, make sure to rinse hair thoroughly after the vinegar rinse. Martha swears she doesn't have to wash her hair again for several days. (And yes, there is a slight vinegar odor for a day or so, she reports).
Unfortunately, I can't recommend this rinse for colored hair. The acid can strip away your pricey investment.