SearchBox Companion Rated 5 out of 5 stars
What is unique to this add-on is that you can search for separate words (or separate phrases) with just one click. You don't need to run a new search for each word as you do with the find toolbar.
There is however a small bug. Sometimes the search box breaks up when you customize your toolbars, especially if the search box is not empty (the words in the search box appear in the navigation toolbar).