1.
ACP --> Usersgroups --> Usergroup Manager --> Edit Usergroup (GO) --> Username HTML Markup....you can use this:
Code:
<span style="color:#000000;"> </span>
...change #000000 to whatever html colour you want.
2. You could use a user title:
ACP --> Usersgroups --> Usergroup Manager --> Edit Usergroup (GO) --> User Title
Otherwise, it would require custom coding -- shouldn't be too hard.
Regards Jason