Bon Plan Gratos

<p>This plugin gives you the possibility to display ratings on posts / pages and also on Google search results.</p>
<p>It is extremely light, very fast to load, comptabible with all versions of WordPress and will not break any of your plugins. It is inspired of similar existing plugins, but remains very simple. As you know, page speed is a factor to increase Google ranking, as well as the use of rich snippets.</p>
<h4>Important</h4>
<p>Rating function is voluntarily limited to authors (only authors can rate, and not visitors) through the admin panel, in order to remain as light and fast as possible.</p>
<h4>Main functionnalilties</h4>
<ul>
<li>Rating from 0 to 5, with a 0.5 step, in the post edit screen, </li>
<li>Use of Google snippets to help Google to display ratings in search results,</li>
<li>Rating tags detected in Google Webmaster Data Highlighter tools,</li>
<li>No use of javascript / ajax to improve loading,</li>
<li>Different format of ratings available (star, heart, gradient),</li>
<li>Use of sprites to improve loading of PNG images,</li>
<li>Automatic display of ratings in posts, pages or both,</li>
<li>Possibility to display ratings in posts through ‘shortcode’,</li>
<li>Possibility to display ratings anywhere with ‘php function’.</li>
</ul>
<h4>Additional information / help</h4>
<p>More information on shorcode, PHP function, etc… on plugin web page:<br />
http://bonplangratos.fr/wp/plugins/google-quick-ratings</p>


Google Quick Ratings

The lightest and fastest plugin to rate posts and pages by their authors, comptatible with Google rating snippets.

Kemory Grubb

<p>The GoodReviews plugin displays information about a specific title from Goodreads, including reader reviews. This plugin was developed mainly for authors or booksellers who want to showcase Goodreads information about specific titles on their WordPress sites. You must obtain a Goodreads API developer key in order to use this plugin. You can obain an API key by following the instructions at goodreads.com/api. This plugin was developed by a third party who is not affiliated with Goodreads.</p>
<p>Features:</p>
<ul>
<li>Uses a shortcode to display Goodreads reviews and book information for a specific ISBN or Goodreads.com ID in any page or post.</li>
<li>Returns book information in divs and reviews in an iframe that can be styled manually from the shortcode, via custom CSS, or via a built-in responsive style sheet.</li>
<li>Includes three separate widgets that can be used in place of the shortcode.</li>
<li>Supports WordPress localization (i18n)</li>
<li>Uses WordPress 3.8 and later Dashicons to display average ratings.</li>
</ul>


GoodReviews

Display Goodreads.com reviews for ISBNs or IDs you specify on any page or post.

Google Quick Ratings vs GoodReviews