Tried to create a brush that could help in picking colors.
When drawn in the top left corner of your view it draws a palet with the color you picked, some hues to the left and right of it, and the complementary color. The values get darker when you get lower. In the image above pink was the main color, so it shows purple and red to the left and right of it.
It sort of bugs when picking low hues (red/orange), but this was just an experiment anyway
It may be nice to have some brushes that use this more dynamically, e.g. linked to pen pressure or something.