Here are 5 Firefox plugins related to Linux. These Firefox Add-ons are not just compatible with Linux, but have something to do with Linux specifically.
Works with: Firefox: 1.0 – 2.0.0.*
Clear Text Fields
Clear Text Fields allows you to right click form text inputs and clear their contents. This is handy for Linux/X11 users who want to clear a form element but don’t want it’s contents placed in the clipboard, overwriting what you intended to paste into it.
Works with Firefox: 1.5 – 2.0.0.*
Konquefox is an extension for Mozilla Firefox that adds some useful buttons: Clear URL, Go Up and Zoom, for a better integration in Linux or KDE environment.
Works with: Firefox: 1.5 – 3.0b4
Ubuntu Human Theme for Firefox
Ubuntu Human Icons, derived from Ubuntu Linux OS. Tested in Ubuntu Linux, other Linux and Windows (including Vista).
Works with: Firefox: 2.0 – 2.0.0.*
Ubuntu Forums Menu Plugin for Firefox
Additional navigation menu for Ubuntu Forums via main-menu and context menu.
Works with: Firefox: 1.0 – 3.0a8