I don't know where you live, but I get my hair done at John Masters in NYC - he just came out with a line of organic hair coloring, his salon is ammonia free and the products have little to no chemicals and are not animal tested (and his salon is wind powered! not sure how.....but I believe what they say!). Another idea would be to go the henna/hemp route.
I live in Los Angeles, so New York is a little too far away. I love Aveda make up and beauty products so I may check out their hair dyes - although I hear those still have chemicals in them, just fewer chemicals. Is using Henna hard? I used to have dorm mate in college who dyed her hair with henna.
I just checked and Aveda's hair coloring is really expensive - I have enough trouble affording a haircut as it is. I might try it in the future though, if I plan ahead put aside some money for it. Thank you for the suggestion though!
Please for the love of god don't use henna. Henna is only good if you keep your hair the same color all the time. If your someone who likes to change your color fairly regularly than do not do henna. I made that mistake and I ended up buzzing my hair when I decided to go back to my natural hair color. Henna coats the shaft of your hair so that it can't be penetrated by regular dye, so once you use henna you can only use henna until you cut off the part that you colored. Herbatint I've heard is pretty good but I haven't used it myself. I've used Tints of Nature and absolutely loved it. It honestly makes your hair softer and shinier than before you dyed it. I bought it at my local health food store but I've seen it at Whole Foods and I know you can buy it online. Hope that helps!
I ran across a couple of at home natural colors that look interesting. I haven't tried either yet, but am planning to try one next time. One is called Palette by Nature, and one of the guys who created it used to work for Aveda:
I live in Los Angeles too and I go to Shades All Natural Color in Beverly Hills on Robertson. I go to Kiki there - she is awesome! Susan Henry the owner also has a take home kit that you can buy that is very affordable for home dyeing. Anohter option is always Aveda. They have cleaned up their act quite a bit, but I feel like Shades is a better option.