I heard cinnamon and conditioner helps. There's like a huge thread about honey lightening in some forum somewhere. You can google it or I can find it for you if you like. I really recommend you looking at it. They pretty much experimented about it, posted their results, and tried to find the dilution ratio that works the fastest. And they have a list of pure raw honey. And what you can add, like olive oil cinnamon to make it work better.

I've also done lemon sprayed in my hair out in the sun and sometimes hydrogen peroxide just for a while.. Though I don't recommend it cuz it can be drying but it worked pretty well. I have highlights from the lemon as a spray and the peroxide lightened my hair over all cuz I used it in a rinse. Just make sure you dilute it and condition your hair.