I perform a lot of prototyping in the Firebug console. Since most of this prototyping refers to the TargetContent frame (component area), not the header and main window, I find it easier to change out the URL to just the "psc" core content URL, eliminating the header frame. When navigating from a homepage, this URL change is a matter of just replacing the /psp/ in the browser's URL with /psc/. When navigating from some other transaction, however, it is not so easy. The URL in the browser is for the first component opened with that browser which may or may not be the current component displayed on the screen. Here is a quick one-liner that I use in the Firebug console to remove all of the PeopleSoft "chrome", leaving just the transaction area:
window.location.href = frames["TargetContent"].strCurrUrl.replace("/psp/", "/psc/")
Better yet, drag the "bookmarklet" link onto your bookmarks toolbar to add this one liner to your browser favorites. Then when you want remove the PeopleSoft header (and left menu on older versions of PeopleTools), just click the bookmark/favorite.