Grégory Viguier

With this plugin, administrators can change the default author base in the registered users profile url, and the author slug of each user. 
Changing an author slug is a good thing for security (if your login is “This Is Me”, your slug will be “this-is-me”, a bit easy to guess). 
The plugin adds 2 fields for this purpose, one in permalinks settings, the other in a user profile.
<ul>
<li>Default: example.com/author_base/author_nicename/</li>
<li>Customized: example.com/jedi/obiwan/</li>
</ul>
<h4>How to edit the slugs</h4>
<ul>
<li>Go to Settings > Permalinks to edit the author base: “author” => “jedi”</li>
<li>Go to Users > “Any user profile” to edit the user slug: “agent-smith” => “obiwan”</li>
</ul>
<h4>Translations</h4>
<ul>
<li>English</li>
<li>French</li>
<li>German by <a href="https://wordpress.org/support/profile/carny88" rel="ugc">Carny88</a></li>
<li>Spanish by <a href="https://wordpress.org/support/profile/oliverbar" rel="ugc">Oliver</a></li>
</ul>
<h4>Multisite</h4>
<ul>
<li>The plugin is ready for Multisite.</li>
</ul>

SF Author Url Control

Allows administrators or capable users to change the users profile url.

num8er

Simply write title to a post and You’ll see that it automagicaly makes slug from title.
History: 
I was searching for plugin that will ease the process of making posts. 
Writing same thing twice (first title, second slug for title in permalink) is like a hell when You’ve to write many posts a day. 
So I decided to make the plugin that will generate slug-string-for-permalink automatically.
Result: pretty simple and useful plugin.
Hope You’ll enjoy it.
Sincerely, 
Anar Jafarov (a.k.a. num8er)

Auto-slug

This plugin generates unicode slug from title You're writing and replaces %postname% part of permalink.

SF Author Url Control vs Auto-slug