Incursor

Mozilla Labs has made an extension for firefox that enables lightweight theming. This means that you can easily make and use custom themes without having to know the normal theme making process.

Here’s an example of the Groovy Blue theme:

<<<Clicky there

You can access the menu through the Tools menu or by clicking the little fox in the status bar.

To make your own, all you have to do is create a header image and footer image.

More information here:

http://labs.mozilla.com/featured-projects/#personas

And how to design one here:

http://people.mozilla.com/~cbeard/personas/designers/

(Load up your design by going to Preferences in the persona menu)