Just as you can add a personalized cover to your Flip camcorder, or "skin" your media player, you can add a "Persona" to Firefox. Go to http://www.getpersonas.com/ and look through the gallery, or check out this one of one of my four-footed local neighbors: https://www.getpersonas.com/en-US/persona/174914 .

If you're browsing with Firefox (sorry, it doesn't work in Internet Explorer,) when you find one you like click "Wear It" or "Wear This Persona". Your picture now covers the entire toolbar.

You can create your own as well, it's as simple as creating a couple of JPG or PNG files. Go here to get started: https://www.getpersonas.com/en-US/upload   It does require the free Personas plug-in to use.