I'd like to be able to adjust the brightness of an entire color map using something similar to the gimpbrightnesscontrasttool. It's intended for use in the Exult game engine that was designed to run Ultima 7. GIMP palettes can be imported for use in various lighting level simulating palettes.
This is mainly due to talk of possibly being able to use 256 colors for each individual shape. End users would need to be able to easily convertible and test the palettes.