Firefox 3 is released but most of the extensions are still not compatible with the new browser, here is a little hack to get your must have extensions work with the new browser, but before proceeding do keep in mind that this can be risky and may render your browser insecure, so proceed on your own risk, I tried it myself and everything works fine, All of my favorite addons like - Linkify, Rapidshare Link Finder, Remove Cookies etc. are working perfectly.
Recently Firefox 3 Beta 3 got released for download, and like everybody else I was tempted to test the browser, but lack of support for my old extensions and the BETA tag prevented me to upgrade, fearing loss of my existing pimped up browser configuration, but there existed a solution for my problem allowing me to use Firefox 3 Beta with my older version of Firefox, and that was portable Firefox 3 Beta 3 meant for portable devices like removable USB drives, I tweaked the existing portable version to make it more suitable and efficient for installation on hard-disk usage and here it is for you to enjoy the much improved Firefox 3 Beta 3.
Faster performance and new sleeker GUI makes working with Firefox 3 a pleasant experience, With nearly 2 million lines of code changes, fixing more than 12,000 issues - Firefox 3 is based on the new new Gecko 1.9 Web rendering platform, including major re-architecting for performance, stability, correctness, and code simplification and sustainability.
The most notable changes in this version are:
Location bar & auto-complete: type in all or part of the title, tag or address of a page to see a list of matches from your history and bookmarks; a new display makes it easier to scan through the matching results and find that page you're looking for. New in Beta 3 is an improved search algorithm which calculates the recency and frequency of a visit to come up with a frecency score that is used to determine the most relevant results.
Download & Install Add-ons: the Add-ons Manager can now be used to download and install a Firefox customization from the thousands of Add-ons available, When you first open the Add-ons Manager, a list of recommended Add-ons is also shown.
Tags: associate keywords with your bookmarks to sort them by topic.
One-Click Easy Site Info : Click the site favicon in the location bar to see who owns the site and to check if your connection is protected from eavesdropping. Identity verification is prominently displayed and easier to understand. When a site uses Extended Validation (EV) SSL certificates, the site favicon button will turn green and show the name of the company you're connected to.
"Stop AutoPlay" is a free firefox extension to block annoying autoplay media on webpages like background sounds and auto-start movies, Stop Autoplay will stop the auto-loading media and allow you to control whether to play it or not.
To block the autoplay of the embedded media, you have two modes to choose:
Disable only the autoplay of the embedded media. In this case, the media file will still be loaded and embedded when page is loading. Press the Play button of the controller when you want.
Block the media when loading a page. It will be replaced by a red frame with a play button in the center. Click in the red frame to load and then play it.
It is advised not to use this extension with Flashblock extension for Firefox.
Firefox 3 is released but most of the extensions are still not compatible with the new browser, here is a little hack to get your must have extensions work with the new browser, but before proceeding do keep in mind that this can be risky and may render your browser insecure, so proceed on your own risk, I tried it myself and everything works fine, All of my favorite addons like - Linkify, 
Recently Firefox 3 Beta 3 got released for download, and like everybody else I was tempted to test the browser, but lack of support for my old extensions and the BETA tag prevented me to upgrade, fearing loss of my existing pimped up browser configuration, but there existed a solution for my problem allowing me to use Firefox 3 Beta with my older version of Firefox, and that was portable Firefox 3 Beta 3 meant for portable devices like removable USB drives, I tweaked the existing portable version to make it more suitable and efficient for installation on hard-disk usage and here it is for you to enjoy the much improved 
"Stop AutoPlay" is a free firefox extension to block annoying autoplay media on webpages like background sounds and auto-start movies, Stop Autoplay will stop the auto-loading media and allow you to control whether to play it or not.