Kristopher Lagraff

This plugin enables the short link menu item to display in the admin toolbar. This feature was removed from 
version 3.3 by default.

Reenable Shortlink Item In Admin Toolbar

This plugin will display the shortlink menu item in the admin toolbar.

Andrew Norcross

Creates a YOURLS generated shortlink on demand or when saving posts.
Features:
<ul>
<li>Optional custom keyword for link creation.</li>
<li>Will retrieve existing URL if one has already been created.</li>
<li>Click count appears on post menu</li>
<li>Available for standard posts and custom post types.</li>
<li>Optional filter for wp_shortlink</li>
<li>Built in cron job will fetch updated click counts every hour.</li>
</ul>

YOURLS Link Creator

Creates a custom short URL when saving posts. Requires your own YOURLS install.

Reenable Shortlink Item In Admin Toolbar vs YOURLS Link Creator