Alex Raven

Report Post is a highly customizable plugin that lets your visitors to report posts or pages with inappropriate content. All these reports are displayed as a table in your Administrator section so you can decide what to do next: edit contents, unpublish posts/pages, or just delete these reports. The plugin was designed to work in both automatic and manual modes. In automatic mode, the link to report will be added to post’s meta box. In manual mode, you can place the link, button or image anywhere you want in templates.
Features:
<ul>
<li>Easy to use – you can simply activate the plugin and it will do the thing</li>
<li>Highly customizable via Options and CSS</li>
<li>AJAX based – no page reload will occur</li>
<li>Can be used in Automatic and Manual modes (to use in templates)</li>
<li>Works for Posts, Pages and Custom post types</li>
<li>Supports AJAXly loaded posts, ‘infinite scroll’ posts, etc.</li>
<li>Does not use additional databases / tables anymore. All reports are stored in postmeta.</li>
<li>Modal window instead of expandable form (works with AJAXly loaded posts!)</li>
<li>Bulk Unpublish, Publish, Delete Posts, Delete Reports</li>
<li>All texts displayed in front end are customizable via Options</li>
<li>Admin notification about reported posts</li>
<li>Can use Captcha to protect from spam</li>
</ul>
Plugin demo: www.esiteq.com/projects/wordpress-report-post-plugin/
<h3>Usage</h3>
Plugin handles 4 class names. Two pre-defined (.report-post-link for a simple link with exclamation mark icon and .report-post-button for button) 
and two custom that you can define yourself (.report-post-custom-link and .report-post-custom-button, respectively).
To work correctly, report link must be placed inside of an
<
article> tag. Article tag must have id=”post-XXXX”, where XXXX is the id of current post. If your theme does not use
<
article> tags, you can add post-id=”XXXX” attribute to report link, e.g.
<pre><code><a href="#" post-id="<?php echo $post->ID; ?>" class="report-post-link">Report Inappropriate Post</a>
</code></pre>

WP Report Post

Highly customizable plugin to let your site visitors to report posts with inappropriate contents to administrator / editor.

Marcel Pol

Report Post is a highly customizable plugin that lets your visitors report posts or pages with inappropriate content. All these reports are displayed as a table in your Administrator section so you can decide what to do next: edit contents, unpublish posts/pages, or just delete these reports. The plugin was designed to work in both automatic and manual modes. In automatic mode, the link to report will be added to post’s meta box. In manual mode, you can place the link, button or image anywhere you want in templates.
Features:
<ul>
<li>Easy to use – you can simply activate the plugin and it will do the thing</li>
<li>Highly customizable via Options and CSS</li>
<li>AJAX based – no page reload will occur</li>
<li>Can be used in Automatic and Manual modes (to use in templates)</li>
<li>Works for Posts, Pages and Custom Post Types</li>
<li>Supports AJAXly loaded posts, ‘infinite scroll’ posts, etc.</li>
<li>Does not use additional databases / tables. All reports are stored in postmeta.</li>
<li>Modal window instead of expandable form (works with AJAXly loaded posts!)</li>
<li>Bulk Unpublish, Publish, Delete Posts, Delete Reports</li>
<li>Admin notification about reported posts</li>
<li>Optional spamfilter to protect from spam</li>
</ul>
<h3>Usage</h3>
Plugin handles 4 class names. Two pre-defined (.zeno-report-post-link for a simple link with exclamation mark icon and .zeno-report-post-button for button)
To work correctly, report link must be placed inside of an
<
article> tag. Article tag must have id=”post-XXXX”, where XXXX is the id of current post. If your theme does not use
<
article> tags, you can add post-id=”XXXX” attribute to report link, e.g.
<pre><code><div class="zeno-report-post-link">
 <a href="#" name="zeno-report-post-link"
 class="zeno-report-post-link zeno-report-post-link-frontend"
 data-zeno_report_post-post-id="<?php echo (int) $post->ID; ?>"
 data-zeno_report_post-post-title="<?php echo esc_attr($post->post_title); ?>">
 Report this Post
 </a>
</div>';
</code></pre>

Zeno Report Post

Highly customizable plugin to let your visitors report posts with inappropriate content to administrator / editor.

WP Report Post vs Zeno Report Post