FlagTab parece ter o que você precisa.
- Persistently Mark Tabs That Match a Certain URL/Regex
Persistent URLs are URLs that you want to always color with a certain label. The Mozilla Add-ons url has already been defined and will always color tabs red (until you change or delete it of course ;). Valid inputs for the URL text box can be flat URLs or regex strings. Once a URL has been set, select the label you want to color it, and hit OK. FlagTab will apply the Persistent URL label OVER the previous label, that way once you navigate away from the Persistent URL the color will be restored to its previous state. Use the "x" button to remove a label and the "+ Add Color" to add a new label.