Assign colored stripes to favicons, based on wildcard paths.
Ever find yourself with tons of tabs open; many with the same favicon and often the same page title? It's difficult to know at a glance which tab is which without clicking to it.
This extension lets you target URLs with a regex match pattern (so .*\.local.* for my local environment) and apply effects to the favicon. I've got my local dev environment with a green stripe across the top, the staging server with a yellow one, and could set different production environments with different colors and effects.
You could also match and apply effects for different signed-in Google accounts, to know which Google Drive is open, or any number of useful things.