Originally Posted by HTMLBasicTutor
Get Web Accessibility Toolbar
(available for IE and Opera).
Shows heading tags on screen.
Also has lots of other helpful stuff that isn't just accessibility related.
Actually, Sir, Opera has been providing a couple of highly useful features for this purpose. In the latest version, the menu structure has changed a lot so just go to Opera Menu >> Page >> Styles >> Block Structure.
As simple as that. No need to install any toolbar for that, unless one needs the extra features of the toolbar that you mentioned in your post (for Opera users).