In the rich text editor:
@mauled000
In a comment:
[mauled000](https://chowlings.com/user/mauled000)
For Names and Avatars:
In the rich text editor:
%mauled000
In a comment:
[![mauled000's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/mauled000) [mauled000](https://chowlings.com/user/mauled000)