Custom header messages for different user groups

[Flexo]

I´m almost sure I saw this once before, but I can´t seem to find it.

Is there a mod that ("which?) allows you to change the header messages, depending on what user group is visiting the forum?
E.g. something lik "Hey, visitor, why don´t you register? Once registered, you can bla this and bla that." for guests, or "Hey there, it seems you haven´t checkes your mails yet, since you have registered but not yet activated your account" and so on and so forth.

Does anybody know which one I´m talking about?