It's All Text! is a Firefox pluging that allows you to use an external editor such as Vedit for editing any text area in any web form.
Just click the blue button that is added at the lower right corner of the text area, and the text will be transferred to Vedit for editing. When you save the file in Vedit, it is transferred back to the text area in Firefox.
It's All Text! is especially useful for editing Wiki pages. One advantage is that it does not convert UTF-8 characters into Windows character set (which would cause any non-ANSI characters to be destroyed).
You can download the plugin from the Mozilla.org link below.