Lobste.rs

On the Linux side of things, I use KDE's "Activities", which are basically OS-level workspaces on steroids.
I set a differently colored wallpaper for each Activity and I have a translucent panel to make this wallpaper color visible even when windows are covering the screen and KDE can also set the application theme to use the wallpaper color as the highlight color.

So, long story short, I can group whole sets of applications windows into different colors, which is pretty cool. Although I can certainly also see the merit of using colors at a more detailed level.