Stargazer

<h4>An easy and effective solution against Comment Spam</h4>
<p>WP-BlackCheck combines various ideas to protect your blog from spam.</p>
<h4>Fearures</h4>
<ul>
<li>Easy Installation</li>
<li>Block known spammers</li>
<li>Block Trackback/Pingback spam</li>
<li>No need to adjust default templates</li>
<li>Spam counter on the dashboard</li>
<li>Statistics</li>
</ul>
<h4>Languages</h4>
<ul>
<li>Albanian (thanks to Taulant Ceka – http://sem.al )</li>
<li>English</li>
<li>German</li>
<li>Slovakian (thanks to Black Cat Artworks – http://blackcatartworks.eu/ )</li>
</ul>
<p>If you want to see this plugin in your language, feel free to contact me or use <a href="https://www.transifex.net/projects/p/wpbc/resource/plugin/" rel="nofollow ugc">transifex.net</a> to contribute.</p>
<h4>Links</h4>
<ul>
<li><a href="http://my.stargazer.at/" title="Authors blog" rel="nofollow ugc">Blog</a></li>
<li><a href="http://bugs.stargazer.at/" title="Bugtracker" rel="nofollow ugc">Bugtracker</a></li>
<li><a href="http://www.twitter.com/ToeiRei" rel="nofollow ugc">Twitter</a></li>
</ul>
<h4>History</h4>
<p>Blocking spammers via htaccess or other server settings would do the job, but that would require<br />
to keep all the files in sync. So I decided to write a centralized solution that enables<br />
innocent users to remove their IP from the blacklist via removal request. As a blacklist gets queried<br />
way too often, I added some local detection of spammers to reduce load at my side.<br />
By now many additional features have been added, making this plugin a full grown anti-spam solution.</p>


WP-BlackCheck

WP-BlackCheck is an Anti-Spam Solution for Wordpress blocking spam using local detection and a centralized Blacklist Service.

Wagner

<ul>
<li>Block certain kinds of users from registering to your WordPress site by adding blacklist rules. </li>
<li>Super simple to use. The whole plugin just has one simple settings page.</li>
<li>Support regular expression rules.</li>
<li>Completely free.</li>
<li>Support tracking and recording login attempts since v1.1.0.</li>
<li>Login attempts chart since v1.1.0.</li>
</ul>


Geek Mail Blacklist

Block users with certain emails from registering to your WordPress site by adding blacklist rules.

WP-BlackCheck vs Geek Mail Blacklist