My list of Firefox extensions as of today.
Tab Mix Plus – Gives much better control over Tab appearance and functionality, as well as including a Session Manager. Well worth the download
FireBug – For all your web page development tasks. CSS, Javascript, Ajax development. Layout problems etc. Well worth checking out and installing if you do ANY web page development with CSS or Javascript.
Download Manager Tweak Extension – Allows the download manager to be opened in a tab, and a few other minor enhancements.
Image Zoom – for zooming in and out on images.
Feed Your Reader – Will re-direct RSS feeds to your favourite reader. I use this to ‘feed’ them to Feeddemon
IETab – If you want to open a window in Firefox, but it really needs IE, then this extension is for you. Used the IE control inside a Firefox tab.
CSE HTML Validator – if you use the CSE HTML Validator, this plug-in lets you use it on a loaded page. Can have it validate all pages you load, or only when you do a View source. Note, the plug-in works with the free version too.
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Web Developer Extension – Essential if you do any web development. Allows for quick selection of information, and selective control over stylesheets, cookies and other items related to web page design.