A bare copy of Firefox is a wonderful thing, but when you start stuffing it with add-ons it gets even better.
So what are the best add-ons for power users? Here's our top 25:
1. All-in-one Sidebar
All-in-one Sidebar makes Firefox's Sidebar more useful by displaying pretty much anything you might want: source code, downloads, add-ons, page info, entire web pages…
Jealous of Safari's Porn Mode – ahem, Private Browsing? Now you can have it too, with Stealther.
3. Web Developer Toolbar
The name's a clue: the Web Developer Toolbar adds a toolbar containing useful tools for web developers.
Install Instapaper's bookmarklet and you can store interesting things to read later. You can view pages without ads or other distractions, and it works on phones as well as PCs.
FireFTP is an excellent bit of charityware – it's free, but donations are encouraged. It puts a fully featured FTP program right inside your browser.
7. Tab Mix Plus
Get complete control over Firefox's tab handling, from the way tabs look to the way they work, with Tab Mix Plus.
8. User Agent Switcher
Browser sniffers stopping you from seeing sites? Pretend you're using a rubbish browser by changing the user agent string with User Agent Switcher.
9. IE View
Sometimes you need to view or test a page in IE. IE View is a Windows-only extension that makes it a one-click job.
10. IE Tab
Does much the same as IE View, but opens IE within a Firefox tab. Once again IE Tab is Windows-only.
Firefox's RSS support is pretty basic. Sage gives you a fully-featured RSS and Atom feed reader that's a joy to use.
Pretend you're busy working with this excellent boss key. Not only does HideBad replace the current tabs with safe ones, but it zaps your browsing history, too.
13. Download Statusbar
Keep track of and control your file downloads without leaving the main browser window with Download Statusbar.
Download every link or linked image from a web page in one fell swoop, filtering out unwanted file types automatically with DownThemAll.
FoxyTunes lets you control your music player, or take advantage of Yahoo!'s online MP3 player, while you wander around the Web.
16. Gmail Space
So unofficial that Google will probably kill you if it catches you using it, Gmail Space turns Gmail into an online hard disk.
StumbleUpon is the easy way to discover sites that other people liked.
Eliminate annoyances and security risks by blocking scripts and other executable content from sites you don't trust with NoScript.
Don't want to register to read an article? BugMeNot gives you other people's logins.
20. Mouse Gestures
A massive time saver, Mouse Gestures enables you to navigate with a quick flick of the mouse.
21. Fast Video Download
Download embedded video clips with Fast Video Download so you can watch them at your leisure.
ScribeFire is a superb in-browser blog editor that works with everything from LiveJournal to WordPress.com and WordPress.org.
BetterSearch adds previews to search results so you don't end up on irrelevant, malicious or obscene websites. Unless that's what you're looking for...
Flash is often used for in-page annoyances, so FlashBlock gets rid of all of it unless you specifically click on a bit of Flash content.
25. Adblock Plus
Adblock Plus eliminates invasive ads and makes some sites look very weird as a result.