atonyk

This plugin adds the ‘Like’ button and ‘Who Likes’ list to:
<ul>
<li>WordPress posts and comments</li>
<li>BuddyPress activities and comments</li>
<li>BBPress posts</li>
</ul>
It allows for registered users to like the items. And it shows for both registered and unregistered users the existing likes.
The components to show the likes to can be configured on the settings page. For example, the likes can be disabled for WordPress comments.
Likes are saved in the internal WordPress and BuddyPress meta tables. No separate tables are created.
The plugin cleans all its data on uninstallation (but not on deactivation).
You can contribute on – <a href="https://github.com/ansnap/like-and-who-likes" rel="nofollow ugc">https://github.com/ansnap/like-and-who-likes</a>

Like And Who Likes

Adds the 'Like' button and 'Who Likes' list for WordPress, BuddyPress and BBPress.

Scott Taylor

Most ratings plugins contain too much code: inline JavaScript, messy markup, weird CSS. Rate is simple, hardly intrusive, and completely overridable.
A Post/Page/Custom Post Type’s rating is the average of all comment ratings. A user can leave a rating when commenting, and change that rating inline after leaving a comment (if logged-in or Cookie’d).
Don’t be afraid to play around and extend the code: drop a <code>rate.css</code> file in your theme directory and mine won’t even load (by default, Rate stars are transparent with a white border, so you can use <code>background-color</code> to set your stars’ colors)!
<pre><code><?php 
// in this version, you need to insert these functions into your theme for ratings to appear
// you don't have to use the_rating(), the comment_rating() will work by itself, but the_rating() will not

// for a Post, Page, or Custom Post Type (average of all comment ratings)
the_rating();

// for a comment
the_comment_rating();
?>
</code></pre>
Read More: http://scottctaylor.wordpress.com/2010/11/30/new-plugin-rate/

Rate

Most ratings plugins contain too much code: inline JavaScript, messy markup, weird CSS. Rate is simple, hardly intrusive, and completely overridable.

Like And Who Likes vs Rate