johnlawrence

PopuList allows you to track the popularity of your posts on social bookmarking sites reddit, stumbleupon, del.icio.us and digg. When PopuList is activated, a page is added to your dashboard giving the number of times a page has been saved or upvoted.
New in version 1.5 PopuList now also lets you view backlinks as indexed by Google and Yahoo.

Populist

Track the popularity of your posts on social bookmarking sites reddit, stumbleupon, del.icio.us and digg

Florian

A very simple bar for outgoing links in your posts.
Features:
<ul>
<li>Feature a “DiggBar like” or “Facebook like” to all external links in your posts</li>
<li>Whitelist for links that you do not want to apply the WP Super Bar</li>
<li>Share your links easly with facebook, digg, twitter, etc…</li>
<li>You can easly edit WP Super Bar CSS from your WordPress Backend</li>
<li>You can customise text and logo.</li>
</ul>

WP Super Bar

A very simple bar for outgoing links in your posts.

Populist vs WP Super Bar