Check favorites for broken or bad links. It checks for bad links and displays a report if it finds something. Check for 404 links, timeout links.
Stratiform is the ultimate user friendly customization add-on for Firefox. It puts the power in the average user's hands to customize the browser's look.
Switch tabs by scrolling with the mouse wheel in the tab bar.
Double-click action for Firefox -
double-click Link, Bookmark/History to open in new tab (emulate ctrl+click).
CommentBlocker is an addon which essentially blocks, or hides, all unwanted comments on websites you visit. It can be used as either a blacklist or a whitelist for websites, letting you decide what to filter out and what not to.
Switch, close, undo close, jump, new, duplicate, and zoom tab control all through just your left, right, and scroll mouse buttons.
Creates a formatted page from bookmarks.
（alt. "BookmarksHome" for Firefox1.5）
Adds a small badge to your tabs to alert you to (for example) new messages on Facebook. The badge is also visible when the tabs are pinned so you can see when there's something new available.
A simple extension to send web pages to your Kindle instantly
Combine the navigation bar and tab bar into one line with a button for search.
The development of this addon is currently suspended. In the meantime, you can give a try to Puzzle Toolbars for an updated experience compatible with Australis.
NextPlease! is a highly configurable extension that allows you to jump to next and previous links on search results pages, like Google, Yahoo, Ebay, Amazon, and many other sites. NextPlease! can be triggered via keyboard shortcuts, toolbar...