Well the controlpanel>Display Options - Tab - HTML includes.
Has that option.
Using the default header and footer fields.
You can enter php or html in them.
Just like here.
where you see the UBBDevelopers banner above.
In fact you can have a different header or footer per forum. by editing forum details and select custom inserts.
As far as rotating images as I replied.
I have it all contained in the html includes fields. Script and settings.
Settings are a little cumbersome but once you learn them they are easy.