Scott Taylor

Like Buttons makes your site instantly share-able. The plugin adds <code><meta></code> tags to your pages’ HTML <code><head></code> which will pull the proper content from your site when someone shares one of your site’s URLs on Facebook. Using some simple Theme functions, you can add Like buttons to posts / pages / custom post types AND a Like button for your blog / website
<pre><code>// in the Loop - for posts / pages / custom post types
the_like_button()

// a Like button for your blog / website, put it anywhere!
the_blog_like_button()

// use this if you don't want to register your app
the_like_iframe()
</code></pre>
Read More: http://scottctaylor.wordpress.com/2011/01/04/new-plugin-like-buttons/

Like Buttons

Adds Open Graph  tags to your posts/pages/etc, adds a Facebook Like button to posts using simple Theme functions. Requires a Facebook Application ID ( …

Waterloo Plugins

Social Shares uses the Facebook and Twitter APIs to fetch the total number of shares for each of your posts. The number of shares is stored in your database for any plugins to use. Social Shares can optionally display the number of shares on your posts. The number of shares is styleable. You can use the shortcode <code>[social_shares]</code> anywhere in your posts.
In addition, you can sort your posts by the number of shares. You can make a page that displays your posts with the most shares. Simply add <code>?sort_shares=desc</code> or <code>?sort_shares=asc</code> to the end of any WordPress URL to sort by the number of shares.

Social Shares

Get the number of Likes and Twitter Tweets for each post. Sort your posts by share count or display the share count.

Like Buttons vs Social Shares