You asked for it! So here it is. Here is a extensive tutorial about making brushes in zbrush. This will also help when customizing existing brushes.
There are 4 creature brushes included as well!
The tutorial set is 45 minutes in length with 9 videos.
All videos are straight to the point.
Here is a breakdown of what you will learn from this tutorial.
Part 1: Reference Gathering and Deciding Brush Types (dragRect, Spray, Dots)
Part 2: The different types of brushes in Zbrush
Part 3: Getting your document ready
Part 4: Creating a brush from a sculpt in Zbrush
Part 5: Creating a brush from photoshop
Part 6: Creating a stroke dot brush
Part 7: Manipulating the alpha and stroke
Part 8: Saving your Brush
Part 9: Conclusion
I hope you enjoy! Please give me feedback on what you think.