*** due to the latest versions of Firefox removing the Addon-bar I recommend using this extension https://addons.mozilla.org/en-US/firefox/addon/the-addon-bar/ to regain it. A new version of Social Share Counts will be coming soon with a built in fix, but the timeline is unknown, so the extra extension is the fast fix for now.***
"Social Share Counts" is what it says and does what it's named. This social media share checking extension shows counts for Delicious, Facebook, Google Plus, LinkedIn, Pinterest, StumbleUpon and Twitter. Whether its a webpage, an image or a file... All counts are loaded next to official site icons in your statusbar. Social Share Count will show you how much it has been shared. Any URL you can load in your browser will grab the count for Twitter, StumbleUpon, Pinterest, LinkedIn, Google+, Facebook, and Delicious through the official count API's.