jdblundell

This plugin hopes to make linking to Twitter profiles easier in WordPress posts and pages.
It’s the result of typing Twitter usernames far too often in my blog posts and having to go back and link to them later, typing out http://www.twitter.com/username.
The plugin uses a basic shortcode:
[twitter]
to wrap around Twitter user names.
The plugin will then output the username with a link to their profile, displaying the standard @username format.
In addition, the links can be styled via your sites CSS, using the .twitshort selector.
<h3>Usage</h3>
<ol>
<li>Once it’s installed a quicktag/button labled “twitter” will display in your post/page edit toolbar. Clicking the link will insert the [twitter] and [/twitter] shortcode into your post/page. Simply insert the Twitter user’s name between the two short codes and the plugin will take care of the rest.</li>
<li>You can also insert the shortcode manually around the Twitter username you wish to link to. </li>
</ol>
Example: [twitter]jdblundell[/twitter]

Twitter Link Shortcut

A plugin to make linking to Twitter users easier with shortcodes.

wpyb

To prevent that usernames are publically visible, the username in the author’s permalink is replaced with the author’s ID. 
In case the page is invoked with the default permalink structure, it is displayed “Page not found”.
Additionally it is possible to modify the author base. It is recommended to make use of this plugin to change it, but it also works with other plugins that have the functionality to customize the author base.

Change Author Link Structure

To prevent that usernames are publically visible, the username in the author's permalink is replaced with the author's ID.

Twitter Link Shortcut vs Change Author Link Structure