Firefox tip: If you don't like the small size of the Google search box or would like to use the address bar itself as the search box (a la Netscape/Mozilla), replace the 'keyword.URL' property in about:config with 'http://www.google.com/search?q=' (without the quotes). Now you can remove the Google search box altogether from the navigation toolbar.

Mind you, you lose the flexibility of using multiple search engines, though.