I’ve got several Firefox extensions that I simply cannot live without these days.
British English Dictionary
An absolute requirement in this American centric world!
FoxMarks Bookmarks Synchroni(z|s)er
If you use Firefox on more than one computer, you’ll want Foxmarks. Install Foxmarks on each computer, and it will work silently in the background to keep your bookmarks synchronized. You can also log in to my.foxmarks.com to manage your bookmarks from any computer.
HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla. The number of errors of a HTML page is seen on the form of an icon in the status bar when browsing…
Fasterfox allows you to tweak many network and rendering settings such as simultaneous connections, pipelining, cache, DNS cache, and initial paint delay.
FoxClocks lets you keep an eye on the time around the world – or just your local time – by putting small clocks in your statusbar.
I’m nowhere near nerdy enough to have GreaseMonkey installed!