Getting pallettes isn't hard-xwe and inkworks do their job well
Let's say I have 2 pallettes-the Doom pallette and a version with all colors in cyan or a pretty aquamarine (Doom lacks Cyan).
What happens when I go underwater? Instead of this royalblue I could see a nice watery color if it was possible to change pallettes with ACS. This could easily fake the lack of 24 bits in colored sectors
only in this situation tough 
This could lead to some interesting things, like black and whiting the player's view and such (Zdoom doesn't support tricks with the invulnerability, that could be done with Inkworks-see Hacx's invulnerability as an example). Or maybe System Shock-esque Berserk patch side-effect? Custom night goggles that brighten everything and invert values (so it becomes bright) and have a nice green tint?
A real use for it (for me or artists who attempt to make their own cutscenes in the game via pictures) would be in making cutscenes from static pictures-more than often the pallette ruins them. What if I could set up a custom pallette for the moment the picture is displayed?
I could get that pallette with Inkworks from that very image and it would remain untouched. The picture would be displayed Strife-intro way so the player wouldn't see the messed up game world by the custom picture's pallette This is actually implemented (see-Heretic's 2nd episode "endpic") but I kindly ask for control over it via ACS.
If the pallettes could also have their own colormaps this would lead to many interesting visual effects
Looking forward.
