Review for Tab Counter by Gapana
Rated 5 out of 5 stars
Correction -- all works now. Curious that it showed up only after my third Firefox restart. Note it appears, by default, and per documentation for those who look, not in the status bar but on the far right of the menu bar. Looks good.
This review is for a previous version of the add-on (1.2).To create your own collections, you must have a Mozilla Add-ons account.