The Doom Retro source port has another neat feature that I'd like to see in PrBoom+: Barons of Hell and Hell Knights now bleed green and Cacodemons now bleed blue rather than red blood when they are injured, corresponding with the blood shown when they die.
Although I have to admit it's all for the lulz, here is the patch that enables this at least for the OpenGL renderer.
Forgot about crushers, fixed now.