Social Share Counts for Delicious, Facebook, Google+, LinkedIn, Pinterest, StumbleUpon, and Twitter for Anything Loaded in Your Browser. Social Site Icons Load in Your Statusbar With Text Counts.
Here is more about the add-on from the developer:
“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.
You can pick up Social Share Counts at the Firefox Add-ons website.