As you can see, my brushes are covered by a Creative Commons Attribution, Non-Commercial Share-and-Share Alike license. However, enough people have now contacted me about commercial use of my brushes that I thought I'd better make a statement about it.
If you would like to use my brushes for commercial purposes or in commercial work, please contact me directly and ask. I do allow commercial use, but it is on a case by case basis. I care about the context in which my brushes are shown and used. So please ask.
Also, if I do allow you to use my brushes on commercial work, I ask you to make a small donation to the non-religious charity of you