Ok, so if you google around, you’ll find some 7,370,000 search results on ‘top  firefox extensions’. But this post is gonna be a bit different. Its not about the universally top Firefox Extensions (if such a thing even exists!), but about the ones which /me uses most! NO recommendations!
Here’s the list (in alphabetical order):

1. DataFox : BSNL DataOne Broadband fuels my Internet. And it has a 500GB ul/dl limit per month. That’s why /me can’t do without the tiny statusbar applet this nice extension provides to keep a tab on monthly usage.
2. Download Helper : The easy way to download YouTube videos to hard disk (when /me is not using youtube-dl script from the CLI i.e.!)
3. Download Statusbar : “View and manage downloads from a tidy statusbar - without the download window getting in the way of your web browsing”. Yeh…works just as advertised, esp. that ‘getting in the way’ bit.
4. DownThemAll : The only download manager /me ever uses, be it on or off the web browser. /me just loves its filtering options.
5. FireFTP : /me’s favourite FTP client.
6. Fire Gesture : The extensions /me uses all the time. Real handy, to the point of making /me kinda lazy!
7. Flashblock : /me hates those silly flash ads eating into my monthly data usage limit, not to mention the elevated page loading times.
8. Identifox / Twitterfox : Ever since /me discovered microblogging, these extensions are his constant companions!
9. InFormEnter : /me is too lazy to type all those form information over and over again.
10. Orkut Toolbar : /me spends lotsa time on Orkut, and this is the BEST orkut related extension for Firefox. Its great that it has recently been updated to spport Firefox 3.5
11. UrlLink : Very useful for converting those non-hyperlinks into hyperlinks and open them in new/same tabs.