The following download sites contain some very useful add-ons for Firefox.

This gives a sidebar which shows thumbnails of the contents of tabs in Firefox.   It is very customisable, can be quickly switched on or off when you want it, and, if you don't like it, can be readily removed without problems.

Another excellent add-on for Firefox which warns and protects against LSO's which have been depsoited on your computer from sites such as Google, Ebay, Youtube, etc.

Again easy to add to Firefox and equally easy to remove without problems if you don't like it.

This simple, but very, useful little add-on automatically loads your homepage(s) when you open a new tab in Firefox.     Does something rather similar to clicking on the 'Home' icon whilst holding down the CTRL key but is quicker to use and you don't have to remember to hold down the CTRL key!

There are many other add-ons and extensions for Firefox available from the Mozilla Add-on website: