CSSMessageWallTags

CSSMessageWallTags allows you to add a customizable "tag" to messages and forum posts by a specified user. It can be used to distinguish administrators, bureaucrats, the wiki's founder etc. It can be used for any purpose.

Note: There is a Javascript alternative to this script.

Code
Add this code to Special:CSS or another CSS page.

Customization
You can use the code below to customize it. Please add it to Special:CSS or another CSS page to let it work. This results in: