3sheep

The plugin allows you maintain a number of separate signatures that can be added into posts and pages using short codes.
You can use ‘Number of Signatures’ option to set the number of available signatures. You can then enter each signature using text and variables to add author information. The available variables include:
<ul>
<li>%LOGIN% – Login name</li>
<li>%FIRST% – First name</li>
<li>%LAST% – Last name</li>
<li>%NICK% – Nickname</li>
<li>%EMAIL% – Email address</li>
<li>%URL% – Website</li>
<li>%DESC% – Description/Bio</li>
</ul>
To include a signature into a page or post use the shortcode shown next to the signaure (e.g. [tssig id=”2″]).

3 Sheep Signatures

Allows adding a custom signatures to posts and pages using shortcodes.

Glenn Ansley

fullthrottledevelopment

This simple little plugin gives each author on your blog the ability to setup a signature and to include it at the bottom of their posts.
The admin screen gives each author the ability to format their signature (a text area with HTML formatting enabled) and to indicate whether or not they want the signature on or off by default.
Regardless of the default setting, your authors may toggle the inclusion of the signature to ‘on’ or ‘off’ for each individual post at the bottom of the Write Post and Edit Post screens.
=Release History= 
 1.4 – Updated for WordPress 3.5. 
 1.3 – Fixed a bug that caused signatures not to show up on certain server configs. 
 1.2 – Moved Signature Management to profile page. 
 1.1 – Fixed a bug that prevented writing / editing pages. 
 1.0 – Initial Release

FT Signature Manager

FT Signature Manager allows your authors to create a signature to be appended to the end of their posts.

3 Sheep Signatures vs FT Signature Manager