I've been making a number of custom brushes for myself, and I thought I'd collect together the best ones and release them. They're a little more advanced than most I've seen, featuring rotation, animation, and pressure sensitivity. Hopefully they will help you.
I imagine I'll be making more brushes in the future, so if you have any requests or suggestions I'd love to hear them. If you can use an image to describe the brush or effect you want, it would be extremely helpful!