Tab Badge 1.6 (Windows)
Source: Geoff Lankow
Adds a small badge to your tabs to alert you to (for example) new messages on Facebook. The badge is also visible when the tabs are pinned so you can see when there's something new available. The badge is based on the title of the page, so if it is "(8) Twitter / Home", a red badge with the number 8 is displayed inside the tab. You can blacklist the badge from any website by right-clicking on it (and as of version 1.2, remove badges from the blacklist).