Just a quick update (thus the pt 3.5) on the status of the Firefox Add-on Overhaul. Some good news from the Mozilla Webdev Blog in response to a complaint (not mine) in regards to the lack of an Advanced Search feature:
February 14th, 2007 at 10:37 pm
…Advanced search is on our list, and will come back.”
You can take a look at the preview site, but just keep in mind that this is a work in progress and due to the issues discussed in the Mozilla Webdev Blog, the site may be inaccessible or not function as desired at times.