Feeling lazy for the holidays - just going to plop these all together.
Spraypaint - pressure is analogous to distance from canvas here (lighter = smaller and more spread apart)
Dual - two tone brush, no overlap from rotation/direction
Shadow - two tone brush, static scatter direction - overlap from rotation/direction makes shadow effect
Tread - silly, looks like a tire tread
Seuratizer - (added 12/25/13, Merry Christmas!) - this is an offshoot of the spraypaint brush. It's chock-full of controllers, but mainly it dances around the selected hue by a few degrees while changing value and scatter distance from pressure. Was trying to make a brush that would emulate pointillism. It works well as a image-based color filter and also for leaves and such.