click the down arrow on left of search bar and use -> Manage Search Engines
note extensions may be available that could help with searches
if you are on a site with a search feature you may be able to add that (eg this site has a firefox support search bar )
■ Search boxes on toolbar
One method would be to bookmark whatever search engines you use . those bookmarks may then be added somewhere useful such as to the bookmarks toolbar. Note you can bookmark specific searches. Some other firefox features may also be useful
Did you read the articles I linked to . Try the following:
Just open the search in a tab.
Bookmark that tab
Add that tab on the bookmarks toolbar (that allows you to open it with one mouse click)
If you wish add a keyword, eg 'g' for google
Now if you go to the location bar,
either by mouse or by Ctrl+L
type g this string into your location bar and hit return it will do a Google search for this string.
repeat steps 1-4 for each search engine but use a different letter eg w for Wiki
I am not aware that we are able to duplicate the search bar, on toolbars. But There is probably some way of modifying firefox to allow that. Possibly firefox 4 is slightly more flexible, it seems to allow toolbars to be expanded to double height for instance.
Meanwhile the solution above is close to what you are trying to do, it merely requires you to type one additional letter, but use the location bar instead of the search bar.