 <p>I've been using the Mozex extension for Firefox for years.</p> <ul> <li><a href="http://mozex.mozdev.org/" rel="nofollow noreferrer">http://mozex.mozdev.org/</a></li> </ul> <p>Once installed, on the "Textarea" tab, assign a hot-key and enter the command to run. For example:</p> <pre><code>gnome-terminal -e "/usr/bin/vim %t" </code></pre> <p>When the hot-key is pressed, Mozex will create a temporary file and replace the "%t" above with its name.</p> <p>If there's more than one text area on a page it will allow you to pick which one you want to edit.</p> <p>Mozex provides a lot more functionality than just text area editing. If you want to "view source" with Vim, you can do that too.</p>