As I mentioned in the intro, depending on the color and the exact proportion of ingredients (it's impossible to be 100% precise and accurate when you are making such small quantities) sometimes the pigments don't disperse quite as well as commercial lipstick. If you are applying it with a brush this is not really an issue, because the brush will smooth and even everything out, but if you are using a tube you may need to smack your lips more than usual, or smudge them with your fingertips.
After making my first few colors what should have been obvious from the start finally struck me: this doesn't need to be just lipstick, it can be used as rouge, or face paint! However, I do not recommend using this to paint the area around the eyes. Some pigments are approved for lips and skin but not for the eyes, and since the specific ingredients are not listed on the crayons I would not risk it.
Update: jfarn01 had a great idea which I want to point out here. Crayons can also be used for making colored shoe polish -- it just so happens that I had already posted a recipe for shoe polish here. Just replace the candle in that recipe with 3 crayons of the color of your choice, and you can finally have a polish which matches your shoes.
For up to date news on what I'm cooking up, check out my new blog.