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 ( …

danielfaerber

If you install this plugin on your blog, your visitors get two buttons below your posts and pages:
<ul>
<li>A Facebook “share” button</li>
<li>and a Twitter “tweet” button.</li>
</ul>
These are not the standard Like- and Tweet-Buttons, which also display how many people have clicked on it so far, but basically pure and simple html-links.
DISADVANTAGE:
<ul>
<li>Less interaction.</li>
</ul>
ADVANTAGES:
<ul>
<li>It’s faster. Your blog does not have to contact Facebook’s and Twitter’s servers.</li>
<li>Better privacy. No information about your visitors is sent to Facebook or Twitter. Nota bene: Facebook’s standard like button allows Facebook to track your visitors even if they do not click on it!</li>
</ul>

Fastershare

This plugin allows your visitors to share your posts on Facebook and Twitter, without JavaScript or iFrames.

Like Buttons vs Fastershare