For Adobe Photoshop CS or higher
First three are not custom brushes but I'm adding them to let you know what I normally use. Adjusting the size, opacity, flow, all that jazz~
Air Brush (Hard) is probably the most used brush. Anything from shading to clouds. I sometimes combined the Rocks brush with the Air Brush (hard) to make certain types. The rest is pretty much self explanatory.
Feel free to use these without credit. :3 Just remember that these are not magical. They are just helpful brushes I want to share.