henna will give you hair a reddish-brown color, and its only temporary (washes out completly after 3 weeks, but after a week you already see a major change, it might be good if you live in an african tribe and washes your hair once a week or so, and it'll also protect your hair from the sun, which is its main reason of use)
there is a chinese herb called 'he shou wu', or - 'fo ti' or in its latin name - 'polygonum multiflorum'
it said that it make white hair black, and grow back lost hair.