RE: visually mark off 80th column?

["Drew Adams" <drew.adams@oracle.com>]

> vline would be ideal... but I don't see a way to pin highlighting to
> the 80th column.

You'd have to write a bit of Elisp code, no doubt. I don't have time to look
into it for you, but maybe someone else is interested.

> I've come up with this using the highlight-80+ package.
> (require 'highlight-80+)
> (dolist (hook '(emacs-lisp-mode-hook ... python-mode-hook))
>   (add-hook hook
> 	    '(lambda () (highlight-80+-mode))))

I'm not familiar with highlight-80+. But you can do the same thing with
column-number.

> I really want this to apply to *all* modes, not
> just the ones I thought to list here. Is there any global mode hook
> that applies to everything?

Dunno. It might depend on your Emacs version.
Perhaps someone else has a good answer. 
Maybe `after-change-major-mode-hook'.