I'm really loving Black Ink so far. I never thought I would enjoy designing brushes as much as using them!
My idea is to have a color selector that pops up on screen wherever your brush is located. This has been done before, but I think it would be even better if there were independent keys for Hue, Saturation and Brightness. Normally, when I'm paining, I just want to change the hue or the brightness, but not all three. So, if I could hold down the "H" key and select a new hue, that would be really efficient. Or, if I want to change the brightness, I could hold down "B" and slide up or down to change the value of my brush.
The HUD-style selectors that I've used in the past end up being cumbersome, because they present you with a whole color picker system. It would be great to isolate the HSB values.
If this isn't making sense, let me know and I can try to sketch it out.