The blender pen is one of the more versatile things you can use.
Use with chalk, just dip the tip and paint. You can shade and add more and more color. Start with the lightest shade and keep adding more and more until you have the shading you want
Fairy Dust, Powdered Pearls, and so on...again just dip and paint. When you use the Dove you do not need to seal.
Water color pencils. Color with the pencils again use shading colors and then just color with the Dove to blend.
Watercolor crayons, watercolor bricks anything you want to shade. Even markers.
To clean, just rub the tip on a baby wipe.
Here are some links that may help also:
Blending Pens (RubberStampClub)
Blender Pens (Cloud 9)
Using a Blender Pen (The Stamping Place)