I have seen it around, basically it's a small box at the bottom of showflat.php that would allow you to directly insert text and respond to the topic, of course it would be without all the features like greamlins and stuff, and it would have a link saying that if you want more posting features you should go to postreply.php.
see and example here:
here at the bottom of the page.
I really find that one quite useful and interesting, would it be too difficult to create?
what do you think?
luke01