Wiki Providers Come Together to Offer Universal Edit Button - ReadWriteWeb
http://www.readwriteweb.com/archives/wiki_universal_edit_button.php
"Leave it to people in the wiki market to know how to collaborate. Nearly 20 different wiki providers have teamed up to offer a new Firefox extension that will notify users whenever they are on a page that is publicly editable, using a standard icon that sits in the same place the RSS autodiscovery icon appears. Clicking on the icon (img. on the left) will take you to that page's editing interface."
Wordpress plugin - Universal Edit Button
http://universaleditbutton.org/Wordpress_plugin
"Here's a simple WordPress plugin. Save the following as universal-edit-button.php and place it in the /plugins/ folder, then activate it in admin. "