Firefox: Usable Home Button alters the "Home" button in Firefox so it takes you to the homepage of any website you're visiting. So for example, if you were reading this article with it installed, one click would take you right back to the Lifehacker main page.
You see your actual home page every time you open a new tab or window, so you may not use the Home button that much anyway. On many sites, like ours, the main page is just one click away via the logo or a home link, but where that isn't obvious, this extension could be handy.
UsableHomeButton [Mozilla Add Ons]