For instance, you can get rid of the gray:

Turn gray hair dark again without an expensive trip to the salon or the use of chemical hair dyes. Make your own natural dye using brewed tea and herbs: Steep 3 tea bags in 1 cup boiling water. Add 1 tablespoon each of rosemary and sage (either fresh or dried) and let it stand overnight before straining. To use, shampoo as usual, and then pour or spray the mixture on your hair, making sure to saturate it thoroughly. Take care not to stain clothes. Blot with a towel and do not rinse. It may take several treatments to achieve desired results.

22 more uses here