I like everything about customization. Everyday I use browsers, after switched to Firefox from Safari due to nasty cookies bug on Mac OS X 10.5.6. I starting to enjoy Firefox, version 3.x is faster and responsive. Right now, I am enjoying a customization extension, called Personas. With personas, you can skin Firefox windows into anything you like.
In the beta release Personas, you can assign any background directly into Firefox. But on current release, if you want to create your own theme you must post it to Personas forum. And then wait for approval. This method is for temporary, according to Persona team, they” will create and automated system”:http://people.mozilla.com/~cbeard/personas/designers/, maybe a Persona repository site like Mozila Adds-on.
Meanwhile you can browse Personas gallery site, I think this is a temporary site, because it’s very plain.