Filed under, “not sure if I need it – but thanks, just in case” we have Texto. This add-on for Firefox will allow you to launch an external text editor to edit text forms in Firefox.
Here is a little more about the add-on from the Texto developer:
This add-on strips out much of the Mozex functionality to focus on launching external text editors. Features the ability to customize editor behavior for different websites, and uses the asynchronous process support in Firefox 3.6 to update textareas automatically when the external editor is finished, without polling.