At the fundamental level, EditThisPagePHP basically just let you remotely edit a single page. There are many situations where existing Wiki or Blog software is too complicated, or imposes too much structure. EditThisPagePHP lets you have total control over the HTML -- you can use sophisticated CSS layouts, or very simple HTML -- the software does not get in the way. Life With Alacrity: Simple Yet Sophisticated Group Page Editing
I'm trying to figure out what's so different about ETP. This plus WebDAV might be interesting.