Well, we can always create a theme for Firefox that meets our needs. Check out some other examples of what people used for a "10 foot interface"
The Nintendo Wii. This uses very large buttons to give you a few options. Everything else is either done from the default home page, or not given to you (you can't change fonts and some other settings)
The PS3 has this as their home page. The use the context menu (triangle) to bring up all the options, including "Address Entry" Included a button to "zoom" in.
The Xbox360 doesn't include a browser, but it looks like there is a popular plugin from the MCE to use their browser. Here's a link to a bunch of screenshots for that: http://www.anpark.com/MCEBrowser_Screenshots.aspx
What do people think of the above methods of interacting with the browser on the TV? Personally, I like the context menu for everything, with the possibility of putting the URL on the top of the screen. Also, zoom is a must. Finally, we need to create a TV friendly "home" page that has highly used bookmarked sites contained within large easy to click buttons.
Any other ideas?