Add-ons

DownThemAll! by Nils Maier, Federico Parodi, others

The first and only download manager/accelerator built inside Firefox!

Collector's Note Vast improvement on downloading and the space it takes in your time and on your page.

Dafizilla Table2Clipboard by dafizilla

Mozilla applications allow to select rows and columns from a table simply pressing Control key and picking rows/columns with left mouse button.
The selection can be copied to clipboard but the original table disposition is lost making ugly results wh...

Copy Urls Expert by Kashif Iqbal Khan

Copy multiple urls (links) to clipboard. Provides options to copy urls of all opened tabs and urls in selected text. You can customize the format of copied urls. You can also open multiple links from clipboard.

AutoCopy by Autocopy, Michael Lidman

Select text and it's automatically copied to the clipboard. Also pastes on middle click.

Custom Buttons by Yan, cubegm, others

Gives a possibility to create custom toolbarbuttons...

Google Docs Viewer (PDF, DOCX, PPTX, XLSX, etc...) by Adon

View publicly-accessible PDF, DOCX, PPTX, XLSX, among other files online with Google Docs by only 2 clicks. Click as usual for your default viewer. Support bookmarked URLs. Security and your explicit viewing intention are always honored.

Compact Menu 2 by Milly

Add a compact menu button to the navigation toolbar, and hide the menu bar.

AutoPager by Wind Li

AutoPager automatically loads next pages when you reach the end of a page. It works on a ton of sites,Google,Yahoo..
It works well with most other add-ons adblock plus, WOT and most of the greasemonkey scripts.
You can also try AutoPagerLite.

Hide Menubar by yuoo2k

Supports to hide Menu Bar automatically, you can press the ALT key to show it temporarily.

Copy Pure Text by Scatterplot

Allows to copy selected text as plain text by adding a 'Copy as Text' menu item to context menu.

Edit Bookmark Plus by Kashif Iqbal Khan

Resize 'Add Bookmark' Popup / 'Edit This Bookmark' Popup, fixes tree selection bug, option to disable popup auto close & Update Url and/or Name of a bookmark with the Url/Title of current page.

Replacement of OpenBook addon

Custom Buttons² by SCClockDr, nicholasalipaz, others

The Custom Buttons² Firefox extension provides the code base support necessary to create, maintain, import, and export custom toolbar buttons. The buttons can perform just about any task, with a large number of buttons already available on the exte...