Personas are the easiest way to theme Firefox. Got Firefox? Visit getpersonas.com and it’ll get you started.
If you wanna go “Persona Crazy” you can install Personas Plus for easy access to over 60,000 personas.
Here’s what the Web414 Persona looks like in the Firefox 4 beta. (Don’t worry, it also works in Firefox 3.6.x as well.)
Here’s a close-up showing the logo treatment as it appears in the header. (It looks better in Firefox 4 than Firefox 3.)
I may build more personas if I get time, or maybe I’ll dig into Enhanced Personas. :)