goldenapples

This plugin aims to support community link-sharing, social bookmarking, and discussion of links in the WordPress environment.
This is still at an early stage of what I hope will be a much more ambitious project. If you want to try this out, please give me feedback.
I will guarantee backwards compatibility with all data saved by the plugin, so it should be safe to install and activate, and as I add features, your existing posts and links will work with them just fine.
See the plugin’s <a href="https://github.com/goldenapples/recommended-links/wiki" rel="nofollow ugc">wiki page on github</a> for more up-to-date documentation (its hard to keep documentation updated in multiple places).

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

Recommended Links for WordPress vs Populist