Jared Harbour

Ever want to change the url used to display your posts? This plugin 
allows a blog administrator to change a users url slug from their edit profile page.
The plugin allows for the creation of new author slugs, but also saves old slugs a user has used in the past.

Plugin Name:       Modify Author URL

Allows administrators to modify a users author url from their profile page.

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.

Plugin Name: Modify Author URL vs Custom Author URL