Automattic

John Godley

Donncha O Caoimh (a11n)

Eoin Gallagher

Lenny

Future upgrades to Sharedaddy plugin will only be available in <a href="http://jetpack.me/" rel="nofollow ugc">Jetpack</a>.
Jetpack connects your blog to the WordPress.com cloud, <a href="http://jetpack.me/support/" rel="nofollow ugc">enabling awesome features</a>.

Sharedaddy

Future upgrades to Sharedaddy plugin will only be available in Jetpack.

tanzaho

A plugin that adds three columns to the listing of your articles on your administration. It shows the number of +1, tweets and facebook likes for every post. Like this you quickly see which post received a lot of social attention.
No settings required, just activate the plugin and browse your posts : <code>/wp-admin/edit.php</code>
The plugin does not keep the social count in memory to save speed and to always be up to date.

WordiZ – Admin Social Shares

Plugin that shows the number of +1, tweets and facebook likes for every post in your administration. Quickly see which post received social attention.

Sharedaddy vs WordiZ – Admin Social Shares