Nick Momrik

When writing comments, a lot of people type in google.com, yahoo.com, hotmail.com, and various other web sites which don’t belong to them. This plugin strips out the comment author URL whenever it contains anything from a set of words that you specify in the Options screen. The URL will never make it to the database.

Comment Author URL Stripper

Removes the comment author URL if it contains any of the specified words.

microkid

This plugin gives you full control over the permalinks for author pages. When using “pretty permalinks”, by default URLs to author pages are structured:
http://www.example.com/author/author-name/
With this plugin you can change the “author” part of these URLs into anything you like, for example:
http://www.example.com/editorial/author-name/ 
http://www.example.com/crew/author-name/ 
http://www.example.com/members/author-name/ 
http://www.example.com/posts-by/author-name/
The plugin will also automatically change links throughout your site that point to author pages. The URLs of author feeds are also changed.
Visit the <a href="http://www.microkid.net/wordpress/author-slug/" title="Wordpress Plugin: Author Slug" rel="nofollow ugc">plugin’s homepage</a> if you have any comments questions.

Custom Author URL

Customize the author slug in the permalink for author pages.

Comment Author URL Stripper vs Custom Author URL