A set of tools that helps replicate common watercolor techniques done in the physical real world.
I don't actually do much digital watercolor, but I decided to try my had at a few tools used in traditional real watercolor for the fun of it. The six brushes below:

Drip drop Fun (left) - a dripping watercolor line. Can be used to make big controlled puddles or small dotty drips.
Flecks from Toothbrush - One of the great things about art is how many weird tools you can use. This is a tool that mimics the feeling of putting light runny watercolor on a toothbrush, then flicking the toothbrush across a canvas. It's great for stars, specks, and texture in general.

Salt Assault & Salt Attack - when salt is put on wet watercolor, the salt absorbs the water around it and thus the pigment in the water as well, giving an "erased" effect. This too is great for texturing, like rust or wear on items.
The brush I painted with is the Messy Classroom Watercolor from the Classroom Set I made a while back (ID: 1851416 ) if you're interested in a fluffier watercolor brush!

Paper Towel Blend & Erase (top) - Taking a piece of paper towel and "lifting" excess watercolor off of a page can help create fades. It's a blender as it usually still leaves pigment behind.
Drip Drop Watercolor - The last is just a brush created from the "Drip Drop Fun" to be a normal watercolor brush. It's still sloppy, so feel free to adjust the settings to how you like it.
As usual, please feel free to modify any brush settings to your liking. Turn on or off the border of watercolor, raise or lower opacity & density, do whatever is comfortable for your art. :)
wet and wild