Ben May

This plugin prevents imposters from leaving comments on your website with either the same name or email address as a registered user on your site.
This prevents users on the blog from being impersonated.

Duplicate Comment Authors

Prevents people posting comments using the same name as a registered users display name.

Simon Wheatley

Allows authors to set their location, and then display it on a Google Map.
Adds a template tag: <code><?php al_list_authors(); ?></code> with the following available arguments:
<ul>
<li>include_protected_posts=1 : Include protected posts when calculating the latest post.</li>
<li>echo=1 : Whether to write the map and listing into the page, or return it (so you can assign the HTML to a variable).</li>
</ul>
The HTML output is fairly heavily classed, for ease of CSS styling, but if you need to adapt it you can. Create a directory in your theme called “view”, and a directory within that one called “author-listings”. Then copy the template files from <code>view/author-location/</code> in the plugin directory into your theme directory and amend as you need. If these files exist in these directories in your theme they will override the ones in the plugin directory. This is good because it means that when you update the plugin you can simply overwrite the old plugin directory as you haven’t changed any files in it. All hail <a href="http://urbangiraffe.com/" rel="nofollow ugc">John Godley</a> for the code which allows this magic to happen.
Plugin initially produced on behalf of <a href="http://www.puffbox.com" rel="nofollow ugc">Puffbox</a>.
Is this plugin lacking a feature you want? I’m happy to accept offers of feature sponsorship: <a href="http://www.simonwheatley.co.uk/contact-me/" rel="nofollow ugc">contact me</a> and we can discuss your ideas.
Any issues: <a href="http://www.simonwheatley.co.uk/contact-me/" rel="nofollow ugc">contact me</a>.

Author Location

Allows authors to set their location, and then display it on a Google Map.

Duplicate Comment Authors vs Author Location