Well, I found myself next door to a Sally's this afternoon at lunch time, so I stopped in to see what non-permanent products they had to offer.
I ended up buying Clairol Beautiful Collection in Rich Dark Brown and Ion Color Brilliance in Dark Warm Brown. (Both are semi-permanent products.) Since they are inexpensive, I figured they would be a good place to start. I don't mind coloring a few times a month if I need to, so I'm hoping at least on of the two will give me positive results.
Opsimathia, I decided to stay away from demi products after reading the article that you linked. I know peroxide is not nearly as damaging as ammonia, but I want to stay away from as many chemicals as possible. Thanks for that.
hart4july, I will try the Aveda that you suggested once I'm finished experimenting with the semi-permanent colors that I just bought. I may find it easier to add a little color by conditioning daily rather than applying a product every other week.
For reference, I do have a picture of myself on my profile, although my hair is shorter and layered now. The curls are still there, though. I think the curls tend to disguise the gray more than straight hair would, unless I have my hair pulled up and you can see the streaks at my temples.
Speaking of my temple streaks, I did have my hair pulled up when I stopped at Sally's and the sales associate complimented me on the 'beautiful color' of them. They are almost white, not that washed-out, "dirty" gray that I hear so many people complain about. I can't wait until all of this old color is gone and I can be all-natural.
I'd love to hear more advice if anyone else has any. Thanks!