These tweaks link back to my WordPress Blog and have been tested to work with Firefox 2 builds.
Most of these tweaks do not work with the Firefox 1.5 and have not been tested but may work with the Firefox 3.0 builds.

This list was last updated on: January 1st, 2008:

• Add-Ons & Download Managers in Sidebar - Allows the Add-Ons and/or Download Managers to be opened in a  sidebar instead of pop-up window.
• Add-Ons ‘Install’ Button - Adds an 'install' button to the add-ons manager. ~New!~
• Adding Additional Feed Readers - External link to CyberNet News Article.
• Bookmarks: Backing up and Recovering - A how-to guide on Bookmarks.
• Change Default Text Editor - Changes which text editor Firefox uses by default. 
• Change Progress Bar Color - Tweak  to change the color of the progress bar in the status bar.
• Close Tab Buttons - Changes the way  the Close Tab buttons are displayed. This tweak allows you to have the close tab button at the end of the tab bar (Fx 1.5 behavior), on the current tab, not displayed at all or on every tab (Fx 2.0 behavior). ~Most Viewed/Requested Tweak!~
• Download Manager History Tweak - Changes when completed downloads are removed from the download manager
• Getting Your Search Results In New Tab - Displays search results from the search box in a new tab (instead of the current tab)
• How to Remove ‘Go’ Button - Removes the ‘Go” button from the address bar
• How to Remove The Search ‘Go’ Button - Removes the Magnifying Glass ('Go') button  from the search box
• List All Tabs Button - How to change the location or remove of the List All Tabs Button (down arrow at end of tab bar).
• Moving/Removing Search Box - How to move or remove the search box. 
• Moving the Sidebar - How to move the sidebar from the left side to the right side of the screen.
• Moving The Tab Bar - How to move the tab bar to the bottom of the browser window.
• OpenOffice.org Documents in Firefox - How to open OpenOffice.org documents within Firefox. 
• Quick Find Bar Tweaks - Tweaks to add the ‘next’ and ‘previous’ buttons to the Quick Find Bar and control  how long the bar remains displayed.
• Pause/Restrict/Disable Animated GIFs - How to Pause or stop animated GIFs. ~New!~
• Removing Added Words From Fx Dictionary - How-to remove a word added in error to the Firefox dictionary
• Removing The Throbber - Removes the Firefox 'Throbber' from the toolbar.
• Session Restore Tweak - Allows Firefox to start off where you were when you closed it.  Keeps all windows and tabs intact.
• Spell Check Tweak - Allows the spell checker to check both single and multi-line text area fields
• SSL 2.0 Tweak - Enables SSL 2.0 Protocol still used by out dated sites.
• Tab Overflow - How to change or disable the Tab Overflow (scrolling tabs) feature.
• Transitioning From Netscape 9 to Fx 2 - How to move over from Netscape 9 to Firefox 2