Rated 5 out of 5 stars
This extension is great. Pinned Gmail tabs turn blue by default in firefox to show new email, but not if you are viewing an email thread, only if you are viewing the inbox. With Tab Badge it is impossible to miss that you have a new email.
The only issue I had is it always shows every thread as new on slashdot.org. I added it to the blacklist as http://slashdot.org/ but it didn't work. After removing the http:// and trailing / the blacklist worked fine.