Bookmark Previews adds an album view and thumbnail view to the bookmarks manager.
Adds the ability to print and print preview a web page from the context menu
Lists installed add-ons (extensions, themes, plugins). Compatible version linked from the Developer comments section at the bottom of the addon's page.
Shows you the GET and POST parameters of the current website in the sidebar...
Adds a search box and a filter drop-down to the Addons window, to filter your installed extensions.
Best Firefox Image Uploader (integrates Imgur, Photobucket, and ImageShack)
Supports logging in with your account, synchronization of pre-existing images, uploading of clipboard, dynamic template system for copying image(s) BBCode or HTML source code
Firefox 3 lets you tag your bookmarks, but it doesn't give you a great way to browse your bookmarks by their tags. TagSifter tries to. Select a group of tags in the sidebar or menu, and TagSifter shows you all the related tags and bookmarks. Or searc...
Tabs Open Relative makes all new tabs open to the right of the current tab, rather than at the far right of the tab bar (optionally this only applies to links).
Resize autocomplete popup by mouse dragging
HandyTag simply providing a complete set of most relevant keywords in the bookmark's edition panel. These keywords are retrieved from many different sources.
Change number of visible results shown in locationbar dropdown when searching.
Note: This extension is for Firefox3.0.* ~ 3.7a1pre. This extension might not work on Mac OS X .
SearchPlaces (https://addons.mozilla.org/en-US/firefox/addon/10920) is recommended to a creation of a query and edit.