Probably wouldnt need a plug in. If I were doing it, I'd use a javascript scroller and insert that into the template. Then I'd use template conditionals and phrases to have a unique message for each forum.
I know where it would go... but I don't know where within. It'd go on the FORUMDISPLAY more than likely. You don't need any java or anything. All you need to do is put the following around the title.