What Mod is this?
 

I've seen this on a few other forums and I was wondering if anyone knows what hack it is..

For example if a user is a moderator then it adds _MOD to the end of their username in color, for super moderators it adds _SMOD etc.

Sounds like a template conditional :)

<if condition="is_member_of($post, X)">displaytexthere</if>

wrong, this can be done in usergroup

in the textfield "Username HTML Markup" enter _admin if you want users in admin group to be like someone_admin. and color is possible of course.

same for other groups.

Ouch :D :D :D

Depends on what you want it to do and where you want it to show. remember the musername is not used everywhere.

I think that's what he wants, and to apply all for a username with _mod by using HTML conditions seems too much.