There are some web pages that you tend to refresh every once in a while. While some services like sports play-by-play pages and some webmail inbox pages do, most of them don’t. That is if you don’t use Reload Every – an add-on for Firefox 2.0.
What this does is to add an option to the context menu (right-click menu) to set the page to reload after a length of time that you set. You can also access the settings via a drop-down right next to the reload button.
You can download the add-in here.