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 ( …

Matthias Pfefferle

Adds OExchange and Web Intents support to WordPress’ “Press This” bookmarklet (http://oexchange.org).
Supported Plugins:
<ul>
<li>the webfinger-plugin: <a href="https://wordpress.org/plugins/webfinger/" rel="ugc">https://wordpress.org/plugins/webfinger/</a></li>
<li>the host-meta-plugin: <a href="https://wordpress.org/plugins/host-meta/" rel="ugc">https://wordpress.org/plugins/host-meta/</a></li>
</ul>
From the website:
<blockquote>
This’ll help you get up and running, whether you’re a service that can accept content, a site that has content to share, or a tool of some sort. Remember that OExchange isn’t limited to “sharing” things; it applies to any case where one service wants to send URL-based content to another — microblogging, translating, printing, whatever.
</blockquote>

OExchange

Adds OExchange and Web Intents support to WordPress

Like Buttons vs OExchange