Server Switcher is a navigational help tool for web developers. It allows
you to easily switch between sites on your development and live servers, so
that you can immediately see the differences.

Use case: When you are on http://localhost/page.html (your
development-server) and click the ServerSwitcher-icon you will instantly be
redirected to http://www.yoursite.com/page.html (your live-server).
("localhost" and "www.yoursite.com" are of course configurable)

WWW: https://addons.mozilla.org/firefox/2409/