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

TO DO
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>.

Default Categories

Allows authors to set their default categories for authoring new posts.

Duplicate Comment Authors vs Default Categories