Epiphany is "the" Gnome browser. I have written the extensions below.
My code is available from http://git.sipsolutions.net/epiphany-exts.git, if you don't want to use git let gitweb generate a snapshot for you.
Universal Edit Button
- Displays the Universal Edit Button in the status bar (not in the address bar like the firefox plugin)
- Written in python, simply symlink the two universal-edit-button.* files into ~/.gnome2/epiphany/extensions/.