rainbow-windows package
Adds a color strip to the top of your window to help discern between windows.

Usage
This package exposes several commands in the command palette (cmd-shift-p on mac, ctrl-shift-p on windows and linux):
Rainbow Windows: Toggle: Toggle the color bar on the current windowRainbow Windows: Next Color: Selects the next color for the current windowRainbow Windows: Previous Color: Selects the previous color for the current window